UPDATE FOR ADVANCED 

TECHNOLOGIES TO 

IMPROVE FUEL ECONOMY 

OF LIGHT DUTY VEHICLES 

Draft Final Report 

Submitted to:

US Department of Energy

August 2007

Submitted By:

Energy and Environmental Analysis, Inc.

An ICF International Company

           Energy and Environmental Analysis, Inc. i   

Table of Contents 

1 OVERVIEW .......................................................................................................................................1-1

2 ADVANCED GASOLINE ENGINE TECHNOLOGIES .....................................................................1-1

2.1 INTRODUCTION AND BASELINE FOR ANALYSIS................................................................1-2 

2.2 ENGINE TECHNOLOGY DEVELOPMENT TRENDS .............................................................1-4 

2.3 CONTINUOUSLY VARIABLE VALVE LIFT .............................................................................1-8 

2.3.1 BMW Valvetronic..................................................................................................................1-9

2.3.2 Nissan/Hitachi CVVL ............................................................................................................1-9

2.3.3 Toyota Valvematic..............................................................................................................1-11

2.3.4 Honda AVTEC....................................................................................................................1-12

2.3.5 Hilite Univalve® ..................................................................................................................1-14

2.3.6 CVVL Summary and Analysis ............................................................................................1-16

2.4 CAMLESS VALVE ACTUATION ............................................................................................1-18 

2.4.1 Valeo Camless Smart Valve Actuation - SVA....................................................................1-18

2.4.2 Analysis for Camless Valve Actuation................................................................................1-21

2.5 DIRECT INJECTION SI TECHNOLOGY................................................................................1-22 

2.5.1 Natural Aspirated Stoichiometric DISI Engines..................................................................1-23

2.5.2 Turbocharged Stoichiometric DISI Engines .......................................................................1-27

2.5.3 FEV Turbo DI, VCR, Flex Fuel Engine Concept ................................................................1-31

2.5.4 Spray Guided DISI Engines ...............................................................................................1-32

2.5.5 Direct Injection Summary and Analysis..............................................................................1-39

2.6 REFERENCES FOR SECTION 2 ..........................................................................................1-44 

3 ADVANCED TRANSMISSIONS .......................................................................................................2-1

3.1 INTRODUCTION ......................................................................................................................2-1 

3.2 AUTOMATIC TRANSMISSIONS..............................................................................................2-2 

3.2.1 Mercedes 7G-Tronic, 7-Speed Automatic Transmission .....................................................2-2

3.2.2 Toyota/Aisin 8-Speed Automatic Transmission ...................................................................2-4

3.2.3 ZF 8-Speed Automatic Transmission...................................................................................2-6

3.3 AUTOMATED MANUAL TRANSMISSIONS ............................................................................2-7 

3.4 CONTINUOUSLY VARIABLE TRANSMISSIONS....................................................................2-9 

3.5 ADVANCED TRANSMISSION SUMMARY AND ANALYSIS ................................................2-10 

3.6 REFERENCES FOR SECTION 3 ..........................................................................................2-14 

4 DIESEL AND HYBRID UPDATE ......................................................................................................3-1

4.1 LIGHT DUTY DIESELS ............................................................................................................3-1 

4.1.1 Diesel Technology Advances...............................................................................................3-2

4.1.2 Diesel Exhaust Aftertreatment to Reach Bin 5.....................................................................3-5

4.1.3 Diesel Summary and Analysis..............................................................................................3-6

4.2 HYBRID TECHNOLOGY........................................................................................................3-10 

4.2.1 General Hybrid Product Trends..........................................................................................3-10

4.2.2 Supplier Announcements ...................................................................................................3-13

4.2.3 Summary and Analysis.......................................................................................................3-15

4.3 REFERENCES FOR SECTION 4 ..........................................................................................3-20 
ii Energy and Environmental Analysis, Inc.

List of Figures 

Figure 2-1. Relative Costs and Fuel Consumption (CO2) Reduction for Various Engine Technologies...1-4 

Figure 2-2. Overview of Fuel Economy Potential. .....................................................................................1-6 

Figure 2-3. Pathways for Future Turbocharged Engine Evolution.............................................................1-7 

Figure 2-4. Costs vs. Benefits for Various Advanced Engine Technologies. ............................................1-8 

Figure 2-5. Hitachi/Nissan CVVL Mechanical Implementation ................................................................1-10 

Figure 2-6. Toyota Valvematic CVVLT System. ......................................................................................1-11 

Figure 2-7. Honda’s CVVL Mechanical Implementation .........................................................................1-13 

Figure 2-8. Hilite Univalve® Mechanical Implementation .......................................................................1-15 

Figure 2-9. Fuel Consumption for Hilite UniValve® Derivatives Compared to Other Valve Train Options. 1-

16 

Figure 2-10. Valeo Electromagnetic CVA Design....................................................................................1-19 

Figure 2-11. Valeo’s Camless Valve Engine Fuel Consumption Benefits...............................................1-20 

Figure 2-12. Toyota 3.5L V6 Dual Injection Engine Combustion Chamber Cutaway and Engine Map. 1-24 

Figure 2-13. LS 460 and LS430 Fuel Economy Comparison. Contribution of Various Engine 

Technologies............................................................................................................................................1-25 

Figure 2-14. Toyota New 4.6L V8 Fuel Consumption Comparison to previous 4.3L V8.........................1-26 

Figure 2-16. Fuel Consumption Reduction for Various Boosting Options vs. Relative Cost Increases ..1-27 

Figure 2-16. VW TSI Engine Relative Performance and Fuel Consumption (CO2 Reduction)...............1-29 

Figure 2-17. VW New 1.4L Downsized TSI Engine Performance Compared to 1.6L FSI.......................1-30 

Figure 2-18. Audi A3 Acceleration (80 to 120 km/h) and Fuel Consumption Comparison among Different 

Engine Options (European Data).............................................................................................................1-31 

Figure 2-19. FEV VCR Mechanism and Potential Fuel Economy Contributions from Various Technologies.

.................................................................................................................................................................1-32 

Figure 2-20. BMW Spray Guided Stratified HPI Combustion Chamber Cutaway. ..................................1-33 

Figure 2-21. Fuel Consumption and Performance of BMW 335i Compared to Competition...................1-34 

Figure 2-22. BMW New 3L I6 HPI Engine Map, Fuel Consumption and Operating Modes. ...................1-35 

Figure 2-23. Driving performance and fuel consumption for BMW 530i and BMW 120i with new I6 and I4 

engines.....................................................................................................................................................1-36 

Figure 2-24. Mercedes Spray-Guided DISI Combustion Chamber Design.............................................1-37 

Figure 2-25. Mercedes Stratified Charge Region Map and Fuel Consumption Reduction Potential as 

Compared to PFI......................................................................................................................................1-38 

Figure 2-26. Mercedes CLS350 CGI Exhaust System Configuration......................................................1-38 

Figure 2-27. BMW Estimates for SI Engine Specific Power and Fuel Consumption Reduction Benefits for 

Various Advanced Technologies. ............................................................................................................1-40 

Figure 2-28. Fuel Consumption (CO2) Reduction Potential for Various Engine Technologies...............1-41 

Figure 2-29. Audi 2L TFSI Fuel Consumption and Performance Progression. ......................................1-42 

Figure 3-1. Mercedes 7G-Tronic................................................................................................................2-3 

Figure 3-2. Mercedes S500 Fuel Efficiency Comparison, 7G-Tronic vs. 5AT...........................................2-4 

Figure 3-3. Fuel Economy Improvement, Lexus LS, 8-speed vs. 6-speed................................................2-5 

Figure 3-4. ZF’s New 8-Speed Automatic Transmission. ..........................................................................2-6 

Figure 3-5. Fuel Efficiency Improvement for Various ZF Transmission Designs.......................................2-7 

Figure 3-6. Cross Section of New 7-speed AMT from VW. .......................................................................2-8

Figure 3-7. Fuel Consumption Comparison of Different Transmission Designs from VW. .......................2-9 

Figure 3-8. Bosch CVT Technology Expected Fuel Efficiency Improvements. .......................................2-10 

Figure 4-1. Diesel Efficiency Comparison versus Gasoline by Weight, Expressed as CO2. ....................3-1 

Figure 4-2. Fuel Consumption Improvement of BMW’s New 2.0L Diesel Compared to the Previous 

Generation. ................................................................................................................................................3-3 

Figure 4-3. Fuel Consumption and Performance of New BMW 1-Series Diesel Compared to Previous 

Generation Diesel Vehicles........................................................................................................................3-4 

Figure 4-4. Honda Diesel Technology for the US Market..........................................................................3-4 

Figure 4-5. Basic Configurations for Urea-SCR and LNT-based Diesel Aftertreatment............................3-5 

Figure 4-6. Relative Cost Comparison between Lean NOx Trap (LNT) and Urea-SCR Catalysts. ..........3-6 
           Energy and Environmental Analysis, Inc. iii   

Figure 4-7. Honda Civic HEV 2nd Generation Technology Improvements...............................................3-10 

Figure 4-8. Toyota Hybrid Power Control Unit Relative Power Density Increase, MYs 2004-2007........3-11 

Figure 4-9. GM Hybrid Product Plan........................................................................................................3-12 

Figure 4-10. Valeo StARS Strategy and Fuel Economy Benefits............................................................3-14 
iv Energy and Environmental Analysis, Inc.

List of Tables 

Table 2-1. MY 2005 Engine Valvetrain Technology Penetration by OEM.................................................1-3 

Table 2-2. EEA 2006 Fuel Economy Benefits for Engine Technologies ...................................................1-4 

Table 2-3. Fuel Economy Benefits for Various Intake-CVVL Designs.....................................................1-16 

Table 2-4. RPE [$] Estimates for Intake-CVVL, by Engine Configuration. ..............................................1-17 

Table 2-5. Camless Intake RPE Cost Estimates by Engine Configuration..............................................1-21 

Table 2-6. EEA Estimates for Fuel Economy Benefits and Costs for Various DISI Technologies..........1-39 

Table 2-7. Summary Fuel Economy Gain Estimates for Various DISI Technologies and EEA New 

Recommendations. ..................................................................................................................................1-43 

Table 2-8. Technology Cost Estimates Derived from Bosch Data...........................................................1-43 

Table 3-1. MY 2005 Transmission Penetration by Type and OEM. ..........................................................2-2 

Table 3-2. EEA Earlier Estimates for Fuel Economy Benefits and RPE Increase, Compared to 4-Speed 

AT.............................................................................................................................................................2-11 

Table 3-3. MY 2007 Vehicle Fuel Economy Comparison, CVT vs. 4-speed AT or Manual ....................2-13 

Table 4-1. Light Duty Diesel Fuel Economy Improvement and $RPE Increase........................................3-6 

Table 4-2. MY 2007 LD Diesel Fuel Economy Comparison against Gasoline Models on Equal 

Displacement Basis....................................................................................................................................3-8 

Table 4-3. MY 2007 LD Diesel Fuel Economy Comparison against Gasoline Models on “Competitive 

Performance” Basis....................................................................................................................................3-9 

Table 4-4. Fuel Economy Improvement Potential of Various Hybrid Technologies. ...............................3-14 

Table 4-5. Hybridization RPE Increase and Fuel Economy Benefits.......................................................3-15 

Table 4-6. MY 2007 Hybrid Vehicle Fuel Economy, Key Specification and MSRP Comparison on 

Constant Displacement Basis. .................................................................................................................3-16 

Table 4-7. MY 2007 Hybrid Vehicle Fuel Economy, Key Specification and MSRP Comparison on 

“Competitive Performance Basis”. ...........................................................................................................3-18 
           Energy and Environmental Analysis, Inc. 1‐1   

1 OVERVIEW

Fuel economy has become a focus of legislative activity in response to concerns about 

green house gas related emissions and high fuel prices. Fuel economy standards are 

set by cost benefit analyses that equate the cost of technological improvements to 

vehicles to the benefits realized from fuel consumption reduction and allied benefits of 

reduced GHG emissions and improved energy security. Hence, good information on 

technology attributes to improve fuel economy is essential to the regulatory process. 

Technology continues to develop at a rapid pace and, hence, periodic analyses of 

technologies are required to maintain an up-to-date list of technologies and their costs 

and benefits. EEA has provided the Department of Energy with such periodic analyses 

and this report is an update of a report completed in early 2006 that focused on 

technologies to improve light truck fuel economy. While the technologies to improve 

cars (light duty vehicles) are very similar or identical to the technologies to improve light 

truck fuel economy, this report also has a greater focus on light duty vehicle fuel 

economy. The report focuses only on those technologies where new information has 

become available in the 2006-2007 time frame. 

Section 2 examines new engine technologies and new data has become available on 

gasoline direct injection (GDI), both stoichiometric and lean burn type, variable valve 

timing, camless valve actuation, and turbocharged GDI engines. Section 3 examines 

data on new transmission technologies, notably the new 7-speed and 8-speed 

automatic transmissions, double clutch automated manual transmissions and the 

continuously variable transmission. Section 4 updates an earlier (2004) EEA report on 

hybrid and diesel technologies. The results presented in Section 2, 3 and 4 are 

expected to be used in other subsequent reports that estimate the fleet fuel economy 

potential for the next 20 years.
1‐2   Energy and Environmental Analysis

Advanced Gasoline Engine Technologies

1.1 Introduction and Baseline for Analysis 

This section examines advanced SI engine technology developments and associated 

fuel economy improvement announcements. EEA’s updated analyses for fuel economy 

benefits, and costs for these technologies are provided in this section. The analysis 

builds upon the fuel economy and cost estimates documented in EEA’s previous report 

(EEA 2006).1

 As before, all technology-based fuel economy benefits and associated 

costs are with specific reference to a “baseline” engine, defined as a typical 4-valve 

OHC (single or double camshaft) engine of 2000+ design vintage with fixed valve 

timing. Of course, the actual fleet consists of many engine designs of different vintages 

and different architecture, with differing technology levels. Hence, the baseline by 

manufacturer can be a determinant of future technology potential since some 

manufacturers have already adopted several technologies widely while others have only 

recently begun adopting these technologies. Data for the 2005 fleet is presented to 

show baseline technology penetration by manufacturer. 

As shown in Table 2-1, engines with variable valve actuation are widely used in 

production. The most common systems use VVT (Variable Valve Timing) to control the 

valve opening timing, while the valve lift is fixed. The VVT technology penetration data, 

by OEM indicates that US manufacturers are behind the Japanese in VVT adoption 

rates. DaimlerChrysler did not market the technology in MY 2005, although their newest 

engines, such as the Global I4, were designed with VVT. The VVT adoption rate 

differences can also be partially explained by valve train configuration types since OHV 

engines are generally more difficult to modify for advanced valve technologies. GM still 

uses the OHV architecture in most of their engines, while DaimlerChrysler’s HEMI V8 

OHV engine is a popular option in trucks. The MY 2005 data illustrates that Japanese 

OEMs are not using OHV engine designs. All of their engines in cars feature DOHC 4-

valve technology. Nissan and Toyota provide the same technology in trucks. Some 

Honda LDT engines feature single camshaft (OHC) but, once again, with 4-valve 

configuration. The valve lift control devices are less common and typically are 

implemented in a two-step (or discrete) cam profile switching arrangement. Among the 
           Energy and Environmental Analysis, Inc. 1‐3   

6 major OEMs, Honda is the only manufacturer that achieved high market penetration 

with their VTEC (with 2-step and 3-step VVL) engines. 

Table 1-1. MY 2005 Engine Valve train Technology Penetration by OEM. 

Blank cells indicate “zero” penetration.

 

2 

Valve 

3 

Valve 4 Valve OHV OHC DOHC VVL VVT 

Light Duty Vehicles 

Daimler Chrysler 11.74% 4.94% 83.32% 11.74% 50.84% 37.43% 

Ford 39.71% 60.29% 14.33% 33.79% 51.88% 34.68% 

GM 67.84% 32.15% 61.95% 38.05% 12.27% 

Honda 100.00% 60.32% 39.68% 75.13% 75.13% 

Nissan 100.00% 100.00% 99.74% 

Toyota 100.00% 100.00% 100.00%

Light Duty Trucks 

Daimler Chrysler 75.01% 24.99% 46.41% 44.42% 9.17% 

Ford 43.15% 27.92% 28.93% 11.99% 63.05% 24.97% 18.05% 

GM 67.84% 31.19% 67.73% 1.73 % 30.54% 17.97% 

Honda 100.00% 66.67% 33.33% 100.00% 83.48% 

Nissan 100.00% 100.00% 79.07% 

Toyota 100.00% 100.00% 98.71% 

Direct Injection Spark Ignition (DISI) is a new engine technology with significant fuel 

economy improvement potential, particularly as implemented with turbo-charging and 

engine downsizing strategies. The current market penetration for turbocharged engines 

is very limited. GM and DaimlerChrysler offered the technology on selected sports and 

luxury models in MY2007 and all engines were conventional port injection (PFI). 

Turbocharger penetration for VW even in 2005 is substantial at 32.8% and the company 

offered both PFI and DISI turbocharged engines. The DI turbo engine was new for 2005 

and VW has since expanded this offering to more models. DaimlerChrysler is the only 

major OEM that offers a turbocharged engine in the LDT category (in the PT Cruiser). 

Most non-turbocharged engines with port fuel injection have a compression ratio (CR) of 

9.7 + 0.1 in 2005, while turbocharged engines have compression ratio of 8.1 to 8.8. The 

VW direct injection engine has CR of 12.5. 
1‐4   Energy and Environmental Analysis

1.2 Engine Technology Development Trends 

New information available in the literature was utilized to evaluate the technology 

benefits reported by EEA last year as shown in Table 2-2, and our evaluation indicates 

only modest changes in attributes for select technologies. 

For example, Renault has made available results of their advanced technology fuel 

efficiency improvement assessment, which is based on NEDC testing.2 While details of 

the cost analysis were not disclosed, the fuel efficiency improvement figures are 

available (see Figure 2-1). Renault’s cost curve starts with VVT (about 3% fuel economy 

(FE) improvement). In the mid-range, the downsized PFI (with turbo-charging) is shown 

to provide about 13% fuel consumption improvement (15% FE, which compares to EEA 

2006 more conservative 7% on the US combined cycle). Renault argues that diesels 

provide about 22% CO2 reduction (over 40% FE improvement when converted to 

volumetric fuel economy improvement), which is higher then the EEA 2006 analysis. 

Figure 1-1. Relative Costs and Fuel Consumption (CO2) Reduction for Various 

Engine Technologies. 

Source: Renault European data, with PFI fixed valve timing technology as the base. 
           Energy and Environmental Analysis, Inc. 1‐5   

TABLE 1-2: EEA 2006 FUEL ECONOMY BENEFITS FOR ENGINE TECHNOLOGIES 

SYSTEM CONSTANT ENGINE SIZE CONSTANT PERFORMANCE

FE BENEFIT TORQUE 

INCREASE 

FE BENEFIT ENGINE SIZE 

ADJUSTMENT

INTAKE CAM PHASER 

DOHC 1.4 + 0.3 3.5 + 0.5 1.5 + 0.3 0 

SINGLE CAM PHASER 

(SCP) – SOHC/OHV 1.6 + 0.3 3.5 + 0.5 1.6 + 0.3 0 

DUAL CAM PHASER –

DOHC 2.2 + 0.4 5.0 + 0.5 2.2 + 0.4 0 

TWO STEP VVL 3.5 + 0.5 0 3.5 + 0.5 0 

TWO STEP VVL + SCP 5.0 + 0.6 6.0 + 0.5 6.4 + 0.6 -6 + 0.5 

TWO STEP VVL + DCP 6.4 + 0.6 7.0 + 0.5 8.0 + 0.6 -7 + 0.5 

THREE STEP VVL + 

DCP 6.7 + 0.6 7.0 + 0.5 8.2 + 0.6 -7 + 0.5 

CONTNUOUS VVL 8.0 + 1.0 10.0 + 0.5 10.0 + 1.2 -10 + 0.5 

CYLINDER CUT OUT 6.6 + 1.0 0 6.6 + 1.0 0 

CYLINDER CUT + 

TWOSTEP VVL +SCP 10.0 + 1.2 6.0 + 0.5 11.2 + 1.3 -6 + 0.5 

CAMLESS VALVE 

ACTUATION (em) 13.6 + 1.5 12.0 + 2 16.0 + 2.0 -12 + 2 

DIRECT INJECTION (DI) 3.5 + 0.5 5.0 + 0.5 3.5 + 0.5 0 

DI +DCP 5.5 + 0.6 10.0 + 1.0 7.5 + 0.8 -10.0 + 1.0 

TURBOCHARGING -1.0 + 0.3 37.0 + 3.0 7.0 + 1.3 -32.0 + 2.0 

DI + DCP + VNT 

(TURBO) 4.2 + 1.0 40.0 + 3.0 14.0 + 1.2 -35.0 + 2.0 (fewer cyl.) 

ROLLER CAM 

FOLLOWERS 2.0 + 0.2 0 2.0 + 0.2 0 

Engine Friction Red. I 

(1995+ design vintage) 2.0 + 0.2 0 2.0 + 0.2 0 

Engine Friction Red. II 

(2001+ design vintage) 1.5 + 0.1 0 1.5 + 0.1 0 

Engine Friction Red. III 1.5+ 0.1 0 1.5 + 0.1 0 

Engine Friction Red. IV 1.5 + 0.1 0 1.5 + 0.1 0 

Improved Lube Oil (5W20) 1 + 0.1 0 1 + 0.1 0 

All benefits are in percent relative to port fuel injected engine with fixed valve timing. 

All benefit estimates assume shift point optimization to suit changes to the torque curve. 
1‐6   Energy and Environmental Analysis

 Another new example by Siemens VDO (see Figure 2-2) provides a similar 

assessment, once again, based on NEDC testing.3

 Siemens’ analysis is more detailed 

since it provides the minimum and maximum ranges for fuel efficiency improvement. At 

the smaller FE improvement range, VVT (Cam phasing) is shown to provide a minimum 

of about 2% FE improvement (EEA 2006 - up to 2.2%). The cylinder cut shows 4 to 8% 

FE gain, which matches well with the EEA nominal 6.6%. The Variable Valve Lift and 

Timing (VVLT) is shown to provide a 7% to 9% FE gain, which can be compared to EEA 

minimum 8 + 0.6 % (two-step VVL plus dual cam phaser). 

Figure 1-2: Overview of Fuel Economy Potential. 

Source: Siemens VDO Automotive 

Auto manufacturers generally agree that the combination of turbo-charging, downsizing 

and DISI will be one of the major technologies capable of double-digit fuel economy 

improvements. GM has looked into this technology in great detail and publicized their 

assessment in the 2007 Vienna Engine Technology Conference.4 GM is already 

marketing a few turbocharged engines, including the 2.0L Ecotec, which also features 

DISI. GM is recognizing that, so far, the technology was used to dramatically increase 
           Energy and Environmental Analysis, Inc. 1‐7   

performance but, in the future, downsizing is another technology pathway that can 

achieve substantial fuel economy improvements. 

Figure 2-3 provides a pictorial illustration of the downsized (or enhanced performance) 

and turbocharged engine pathways from GM’s perspective. The company has 

demonstrated that turbo-charging and downsizing can be executed in numerous 

configurations and can be used for both PFI and DISI engines. The package with the 

most promising fuel economy improvement potential is DISI with variable geometry 

turbo-charging and VVT (valve phasing), which agrees with the EEA 2006 

DI+DCP+VNT pathway. Information presented in subsequent sections shows that GM 

and EEA fuel economy estimates are similar for DISI Turbo technologies. GM further 

argues that all downsizing and DISI turbo packages would work well with hybridization, 

since the turbo lag issue can be minimized with the electric motor power assist. 

Figure 1-3: Pathways for Future Turbocharged Engine Evolution. 

Source: GM 
1‐8   Energy and Environmental Analysis

Technology costs are the most controversial research area and detailed public 

information is very limited and is often biased toward a particular researcher or industry. 

EEA did obtain a generalized cost assessment from Bosch and Figure 2-3 summarizes 

this data.5

 The Bosch cost estimates are used in this report in subsequent sections to 

assess EEA’s earlier analysis for discrete technology costs. 

FIGURE 1-4. COSTS VS. BENEFITS FOR VARIOUS ADVANCED ENGINE 

TECHNOLOGIES. 

Source: Bosch 

1.3 Continuously Variable Valve Lift 

The only CVVL system currently in the market is BMW’s Valvetronic, which achieves a 

combination of both lift and valve opening duration change via an intermediate lever 

mechanism working in conjunction with cam phasers. CVVL technology, also known as 

“intake throttling”, allows elimination of the engine throttle unit when implemented with 
           Energy and Environmental Analysis, Inc. 1‐9   

intake VVT. This type of engine can be controlled through real time adjustment of the 

inlet valve lift and intake valve opening times. 

1.3.1 BMW Valvetronic 

The Valvetronic system adjusts the valve lift using a lever positioned between the 

camshaft and the intake valves. The distance from the camshaft is adjusted by 

additional eccentric shaft operated by an electric motor. 

BMW started Valvetronic marketing on its higher-end lineup but now the technology is 

available on most engines. BMW has claimed that the system achieves a fuel economy 

improvement of about 12%, but that this includes the benefit of dual cam phasers and 

reduced friction. Subtracting the VVT benefits, the system is expected to yield about 8% 

fuel economy improvement. This comparison is for FTP cycle conditions and relative to 

PFI (Port Fuel Injected) engine with fixed valve timing and compression ratio. 

1.3.2 Nissan/Hitachi CVVL 

Hitachi has developed a CVVL system, they call VVEL (Variable Valve Event and Lift), 

which is scheduled to be launched on the MY 2008 Infinity G37 Coupe.6, 7 The system is 

designed to throttle the intake valves and works in conjunction with VVT control. 

 Figure 2-5 illustrates the CVVL mechanical implementation. The profile of the output 

cams incorporates ramp section for obtaining smooth lift. The center position of the 

drive shaft is the same as that of ordinary camshafts. Driven by a chain, the drive shaft 

undergoes rotational motion that is synchronized to one-half the rotation of the 

crankshaft. An eccentric drive cam attached to the drive shaft converts the rotational 

motion of the drive shaft to oscillatory motion that is transferred to the oscillating output 

cams by the Link A, rocker arm and Link B. The DC motor mechanism adjusts the link 

and rocker arm kinematics to obtain continuous adjustment of the valve lift. 
1‐10   Energy and Environmental Analysis

Figure 1-5. Hitachi/Nissan CVVL Mechanical Implementation 

Engine developers reported that, at low-to-mid load ranges, the intake throttling 

optimizes the air charge volume. Less valve travel reduces camshaft friction and 

improves acceleration response by allowing more dense air into the cylinders from the 

start of acceleration. The timing control opens the valves for a shorter period, preventing 

blowback of the air-fuel mixture and improving torque. In the high load range, the valve 

lift is increased which allows increased air intake to deliver greater torque outputs. 

For reduced emissions, the intake-valve timing is optimized for cold startup to increase 

the temperature of exhaust gases and more quickly activate the catalytic converter. 

Intake throttling also improves fuel/air mixture formation and emissions through 

increased velocity and turbulence. 

The VVEL improves fuel efficiency most effectively in the low-to-medium operating 

range, thus it is best matched to higher displacement engines that typically operate 

within that range. Nissan has indicated that in high-displacement engines the company 
           Energy and Environmental Analysis, Inc. 1‐11   

will combine VVEL technology with the direct-injection system. Also the system is 

capable of “zero lift”; therefore cylinder deactivation is possible in the future. 

Nissan and Hitachi claim that VVEL adoption, together with VVT, provides up to 20% 

more power and up to 12% fuel economy improvement (cycle conditions were not 

reported). This comparison is against an identical engine without CVVLT, implying a 

fixed valve timing engine. 

1.3.3 Toyota Valvematic 

Toyota announced that it has developed a commercial-ready CVVL system, called 

Valvematic, which is also designed to work with VVT (Toyota’s version, VVT-i -Variable 

Valve Timing-intelligent).8 The new system allows fully flexible intake adjustment and 

eliminates the need for an engine throttle unit. As indicated in Figure 2-6, the overall 

system implementation is similar to other mechanical CVVL trains. 

Figure 1-6. Toyota Valvematic CVVLT System. 

Toyota announcements indicate that the system, installed on a new 2.0L engine (which 

does include undisclosed additional modifications), improves fuel consumption by 5% to 

10% (implying up to 11% fuel economy improvement, depending on driving conditions), 

boosts output by at least 10% and enhances acceleration responsiveness. The 
1‐12   Energy and Environmental Analysis

comparison is likely against the baseline of current Toyota engines all of which feature 

VVT, although cycle conditions are not specified. 

1.3.4 Honda AVTEC 

Honda has announced development of the next generation VTEC (Variable Valve 

Timing and Lift Electronic Control) engine, called AVTEC (or Advanced VTEC). The 

new system will combine the continuously variable valve lift system (intake only) with 

continuously variable timing control.9

Figure 2-7 explains how the system works. To allow the valve lift and timing to be 

varied, the mechanism (1) comprises a camshaft (8) with cams (7), and a pivoting first 

rocker arm (9). The first rocker actuates the end of valve stem (12). The key part of the 

design is a drum (11) which surrounds the camshaft but provides enough opening for 

the cam/follower engagement. 

The drum supports the second rocker arm (10) through pivot point (20). The second 

rocker-end incorporates the cam follower (21). The result is that the other end of this 

rocker (22) actuates the first rocker arm. The valve lift and timing is therefore dependent 

on the position of the second rocker arm, which in turn is regulated by the drum angular 

position. The drum position is adjusted through control members (25, 26). 

Similar to other intake valve throttling designs, Honda’s AVTEC system enables 

elimination of the traditional butterfly throttle. The valve events are then controlled 

according the following principal modes: 

Low-Load. Intake valves close early to achieve a lowered and narrower lift period. 

Since resulting pumping losses after intake closure can be compensated during the 

compression stroke, overall pumping losses are lower. Also throttled intake increases 

air charge velocity and turbulence, improving mixture formation and combustion 

efficiency. 
           Energy and Environmental Analysis, Inc. 1‐13   

Figure 1-7. Honda’s CVVL Mechanical Implementation 10
1‐14   Energy and Environmental Analysis

Medium-Load. The controller creates intake and exhaust valve overlap by advancing 

the intake valve timing to achieve controlled internal EGR. The result is improved fuel 

consumption and reduced emissions. 

High-Load. The valve lift is set high and opening period is widened for improved 

charging efficiency and performance. 

The ability to continuously adjust the transition between these modes is crucial in 

successful system application. Honda has developed a sophisticated controller for this 

design, which allows smooth transition to different engine speeds, optimizing fuel 

consumption, emissions and performance. 

Among many resulting efficiency improvements the new controller allows idle speed 

reduction from 850RPM to 600RPM and still achieves smooth idling. Honda claims that 

this strategy alone resulted in fuel economy improvement of about 1.7% in the FTP 

cycle.11

Overall, the new AVTEC system is claimed to allow for a 13% improvement in fuel 

economy over the current VTEC engines with significant torque increase. Honda’s 

announcements were made in the US so the comparison is potentially for the FTP cycle 

conditions. 

1.3.5 Hilite Univalve® 

Hilite International has announced that the company is refining its versions of DVVL 

technology, called UniValve®, which was developed together with EnTec Consulting.12

The mechanical implementation of the CVVL function is accomplished through the 

eccentric control shaft that contacts an additional link in the valve train, the intermediate 

lever. This additional lever does not have a fixed pivot shaft and is held in position by 

guide and spring. The eccentric shaft moves the lever and controls the bottom “working 

curve” engagement with the roller rocker finger. The eccentric control is driven by 

electric motor via worm gear pair. Figure 2-8 shows how the CVVL function is 

accomplished by this system. 
           Energy and Environmental Analysis, Inc. 1‐15   

Figure 1-8. Hilite Univalve® Mechanical Implementation 13

The mechanism is designed to operate on engines with two valves for the intake side. 

The intermediate rocker arms for each intake valve pair are constructed in a fork 

arrangement. Because of this paired arrangement, Hilite’s design allows the fork 

actuation by separately controlled eccentric shaft. This concept is called “cylinder up 

loading”. The company argues that independent lift control on different cylinders can 

achieve additional fuel consumption savings although issues, such as increased 

vibration and noise, as well as additional controller complexity, still need to be 

overcome. 

Hilite has shown that the UniValve®, when working in combination with dual cam 

phasers, can achieve up to 13% fuel consumption improvement. When combined with 

cylinder up loading, the total benefit is 15% (NEDC cycle). Hilite’s system comparison to 

other mainstream valve actuation technologies, such as two-step VVL and dual VVT, is 

provided in Figure 2-9. 
1‐16   Energy and Environmental Analysis

75

80

85

90

95

100

105

Basic

Engine

Two-Step

Cam

Contour

Switching

Intake and

Exhaust

Cam

Phasers

Two-Step

Cam

Contour

Switching +

Dual

Phasers

Univalve +

Dual

Phasers

Univalve +

Dual

Phasers +

Cylinder Up

Loading

Fuel Consumption [%]

Load Point: 2,000RPM, BMEP=2 

Comparison is for NEDC cycle at constant engine size 

Figure 1-9. Fuel Consumption for Hilite UniValve® Derivatives Compared to Other 

Valve Train Options. 

1.3.6 CVVL Summary and Analysis 

Most OEMs have been reluctant to adopt CVVL because of added cost and complexity, 

which can degrade engine reliability. However numerous new announcements by 

Japanese OEMs indicate that commercialization for the mass market vehicle can be 

expected in the near future.14 Table 2-3 summarizes the fuel economy improvements for 

intake-CVVL from various designs highlighted above. 

Table 1-3. Fuel Economy Benefits for Various Intake-CVVL Designs. 

Comparison is against PFI engine with fixed valve timing/lift and fixed CR, with 

exception of Honda AVTEC, as noted. 

System Fuel 

Economy 

Benefit [%] 

VVT Included 

in FE Benefit? 

Notes 

BMW Valvetronic Up to 12 Yes NEDC 

Nissan CVVL Up to 12 Yes Unspecified cycle 

Toyota Valvematic 5 to 11 No Unspecified cycles 

Honda AVTEC Up to 13 No Fuel economy benefit 

compared to VTEC engine 

Hilite Univalve® Up to 15 Yes European NEDC cycle, w/o 

Individual Cylinder Lift 

Control 
           Energy and Environmental Analysis, Inc. 1‐17   

The fuel economy benefit figures are consistent among most developers. In fact, 

maximum figures reported by BMW, Nissan and Toyota are nearly identical and all 

include VVT contribution. Nissan specifically noted that VVEL contributes up to 12% fuel 

economy improvement compared to an identical engine without it. Honda’s AVTEC 

design, however, shows higher fuel economy benefit and, more importantly, the 

comparison is against already very efficient VTEC engines, which include the two-step 

VVL and VVT. Honda did report that the new engines will be completely retuned with 

redesigned ECU (Engine Control Unit) and likely other measures. Reported specific 

additional fuel efficiency improvements include idle speed reduction (1.7% fuel economy 

benefit). 

Hilite’s UniValve® benefits were derived from European testing, which can not be 

directly compared against the US FTP cycle conditions, so for purpose of this analysis 

the 15% fuel economy figure should be used for reference purposes only. 

EEA has reported earlier that CVVL, when VVT contribution is subtracted, yields about 

8% fuel economy benefit. Additional information obtained does demonstrate that this 

figure is defensible (at constant performance) and should continue being used. In fact, 

the estimate appears to be on conservative side since Honda’s AVTEC solution 

appears to yield higher benefit, if other advantages of fully flexible valve lift and timing 

control, such as idle speed reduction, are more fully implemented. 

Table 2-4 provides cost estimates (converted to RPE) for CVVL derived from figures rin 

the EEA 2006 report . 

Table 1-4. RPE [$] Estimates for Intake-CVVL, by Engine Configuration. 

 I4 I6 V6 V8 

CVVLT 330 400 460 600 

Intake Phaser 52 52 104 104 

CVVL (CVVLT 

minus Intake 

VVT) 

278 348 356 496 
1‐18   Energy and Environmental Analysis

New cost information obtained from Bosch (see Figure 2-4) indicates that BMW’s 

Valvetronic adds about 20% to the cost of the base engine. Assuming a basic I4 (PFI, 

fixed valve timing) cost of $1,100 this figure translates to about $220 incremental cost 

for CVVLT ($RPE about 370). When cost for a single VVT phaser is subtracted, CVVL 

results in about 320$RPE increase. 

Using the same 20% increment, the CVVL RPE can be calculated to be about $430 for 

a V6 and $560 for a V8 (against base engine costs of $1,600 and $2,000 for a V6 and 

V8, respectively). These estimates are within the range of EEA’s earlier figures. More 

importantly, new systems announced by the above OEMs will result in more suppliers 

entering the market and additional savings from economies of scale. As a result, our 

earlier RPE estimates for CVVL are still appropriate. 

1.4 Camless Valve Actuation 

Engine developers have long been interested in Camless Valve Actuation (CVA) since it 

promises as much as 20% improved fuel economy over conventional mechanically 

operated valves. There is less assembly complexity, engine friction and weight with 

camless design because mechanical camshafts and related parts are eliminated. 

Camless valves would eliminate the conventional throttle and, as a result, reduce 

pumping losses. Also, the camless engine with independent valve control would be less 

dependent on fuel quality. The independent valve actuation would be able to control 

residual combustion gases (internal EGR), further reducing pumping losses. Also 

cylinder deactivation can be easily implemented on larger engines. 

This section examines one CVA design by Valeo, which was recently described in the 

literature and is claimed to be close to market introduction. The updated fuel economy 

and cost analysis is provided at the end. 

1.4.1 Valeo Camless Smart Valve Actuation - SVA 

Valeo has made numerous announcements that their SVA technology will be 

commercialized in less than 5 years, for production starting as early as 2009.15
           Energy and Environmental Analysis, Inc. 1‐19   

In Valeo’s electromagnetic camless engine design, each valve is operated individually 

by an actuator that is placed on the upper surface of the cylinder head, directly above 

the valve guides. Each actuator is linked to an engine-mounted Valve Control Unit 

(VCU) that performs the power drive function (see Figure 2-10). 

Figure 1-10. Valeo Electromagnetic CVA Design.

Valeo is developing two different systems, each one including: the actuators, the Valve 

Control Unit (VCU), the wiring rail and the Electronic Control Unit (ECU) with the 

specific strategies dedicated to these new concepts. The first one is called "full 

camless" as it manages the valves on both the intake and exhaust side of the engine. 

The second one is called "half camless" as it manages the inlet valves only.16

Valeo’s current plan is to commercialize the half-camless SVA, which would achieve 

around 80% of the benefits of a fully camless engine, at half the cost. Valeo announced 

that the incremental manufacturing cost for a four-cylinder, half-camless gasoline 

engine would be about $400. 
1‐20   Energy and Environmental Analysis

Valeo confirmed that the main source of fuel economy improvement in the camless 

engine is the increase of the engine thermodynamic cycle efficiency due to pumping 

loss reduction and combustion efficiency improvement (through Miller cycle or 

increased expansion stroke cycle).17 Also some benefit can be realized through idle 

speed reduction. Valeo claims that the half-camless engine would improve fuel 

consumption by about 12% (implying 14% fuel economy gain) and provide 15 to 20% 

more low-end torque than a conventional gasoline fixed valve timing engine. When 

cylinder deactivation benefit is included (implying that the exhaust valves must have a 

separate deactivation mechanism), the total efficiency gain can reach 17% (20% fuel 

economy). These figures were derived under laboratory test conditions. Valeo did 

confirm this data on a test vehicle equipped with 2L I4 under European NEDC cycle 

conditions. The vehicle tests showed that when a transmission is optimized for the 

camless engine operation, the fuel consumption benefit can reach 19% (23% fuel 

economy). Figure 2-11 summarizes these conclusions. Note that the engine is also able 

to reduce criteria pollutants dramatically, especially NOx and CO, primarily through 

internal EGR control and fast catalyst warmup. 

Figure 1-11. Valeo’s Camless Valve Engine Fuel Consumption Benefits. 
           Energy and Environmental Analysis, Inc. 1‐21   

1.4.2 Analysis for Camless Valve Actuation 

Automakers have commented publicly that they are closely following developments for 

camless technology. Companies are concerned, however, that CVA would be costly 

and have uncertain durability once the valve train is not mechanically connected to the 

crankshaft. It appears that primary concerns are not necessarily for valve actuators but 

rather for control system long-term durability. 

EEA has reported previously that camless intake engines are expected to improve fuel 

economy by about 13.6% (at constant engine size), when compared to conventional PFI 

engines with fixed valve timing. Table 2-5 summarizes EEA’s earlier estimates for CVA 

costs. 

Table 1-5. Camless Intake System- RPE Estimates. 

 I4 I6 V6 V8 

Early Introduction Cost (~2012) [$RPE] 500 700 700 900 

Long term cost (>2015) [$RPE] 350 500 500 630 

The cost estimate, when converted to RPE, for Valeo’s system is about $650 which 

appears to be higher than the EEA short-term estimate for a 4-cylinder engine. As a 

result, EEA believes that Table 2-5 costs should be increased by 30% for both short and 

long term costs. 

CVA should deliver at least the same benefits as the CVVLT – or at least 12%, as 

described in the CVVL section. Additional benefit would likely be realized on larger 

engines, when cylinder-cut is implemented. Further additional benefits for all engines 

can likely be realized if additional fuel economy improvements are fully derived from 

advanced controls working with fully flexible intake valve actuation, as illustrated by 

Honda’s AVTEC announcements. 

Valeo’s announcements indicate that automakers are interested in the technology, 

which implies that additional fuel economy benefits are projected from CVA 
1‐22   Energy and Environmental Analysis

implementation. As a result, EEA believes that 13.6% fuel economy improvement for 

CVA is a conservative estimate and could be revised to a higher value. Valeo’s latest 

reported improvement of up to 20%, at constant engine size, appears to be a high end 

value for intake-only CVA fuel economy benefit compared to conventional non-variable 

valve trains. As other manufacturers are expected to report data on this technology 

(Honda recently unveiled a prototype camless engine in Japan), the EEA value could be 

revised upwards to about 15%. 

1.5 Direct Injection SI Technology 

The Direct Injection Spark Ignition (DISI) engines can be differentiated into the 

stoichiometric homogeneous combustion and lean stratified mixture combustion types. 

The stoichiometric DISI process forms a homogenous mixture by injecting fuel into the 

cylinder during the intake stroke and controls the fuel/air ratio in the same way as 

conventional PFI (Port Fuel Injection) engines. These types of engines typically achieve 

some fuel consumption improvements, among other effects, due to intake air cooling 

caused by fuel vaporization directly in the cylinder and the resulting opportunity to 

increase compression ratio. The emissions are controlled by a conventional 3-way 

catalyst. 

The 1st generation lean burn DISI engines achieved mixture formation through a special 

combustion chamber design and are referred to as “wall-guided”. In this type of engine 

the fuel spray injected into the cylinder is guided along the piston cavity wall to form a 

stratified mixture around the sparkplug. With this design, a fuel film inevitably forms on 

the wall. The result is typically higher PM and HC emissions, degraded fuel 

consumption, flame quenching and poor combustion at certain conditions. 18 Another 

wall guided DISI disadvantage is that the stratified combustion is achieved with a wide 

spacing between the injector and spark plug. As combustion timing was difficult to 

control in these engines, ideal efficiency of the thermodynamic process could not be 

consistently attained. 
           Energy and Environmental Analysis, Inc. 1‐23   

The latest generation lean burn DISI systems attempt to avoid the above limitations 

through mixture formation by the spray form of centrally mounted injector, and therefore, 

are called “spray guided”. This process allows small spacing between the injector and 

the electrode. Also, the air-fuel mixture formation takes place independently of gas flow 

and piston movement. This offers an optimum option for raising the fuel economy of 

gasoline engines. Stratified lean combustion has high costs due to complexity of the 

after-treatment process. In the US market, shifting spray-guided operation toward 

stoichiometric combustion has offered a solution to this problem.19

DISI systems combine well with turbo-charging. Conventional PFI turbocharged 

gasoline engines are popular in sports models, and offer excellent nominal power and 

torque outputs. However, these engines often do not offer increased fuel economy, are 

difficult to control for emissions and turbo lag. Many programs have demonstrated that 

these disadvantages can be overcome using DISI. These engines are believed to have 

significant potential to deliver high fuel economy, emission and performance 

simultaneously.20, 21

1.5.1 Natural Aspirated Stoichiometric DISI Engines 

Stoichiometric natural aspirated DISI engines are being used by few OEMs in the US. 

Toyota has introduced this technology in the dual injection 3.5L V6 and 4.6L V8 engines 

used in the Lexus offerings. Volkswagen and Audi are configuring more of their vehicles 

to adopt the technology under the FSI (Fuel Stratified Injection) family name. 

Toyota has adopted a very sophisticated injection strategy that involves both PFI and DI 

injector fueling depending on vehicle operation (see Figure 2-12). The result is a system 

that achieves very high thermal efficiency (as high as 0.36) in the core mid-to-high load 

range, which translates into high power at a reasonable fueling rate. 
1‐24   Energy and Environmental Analysis

Figure 1-12. Toyota 3.5L V6 Dual Injection Engine Combustion Chamber Cutaway 

and Engine Map. 22

The 4.6L V8 was installed on the flagship Lexus LS460. Together with DI, the new 

engine features new VVT, friction reduction and other improvements. The engine 

displacement was increased by about 7% compared to the previous generation LS430 

but the new technology was more than enough to compensate for fuel economy penalty 

resulting from additional displacement and power increase. The final result for LS460 is 

the US combined fuel economy of about 25.3mpg. Figure 2-13 details the performance 

and relative fuel economy improvement contribution of various engine technologies.23

The total engine improvement is 7.5%, of which about one-third (or ~3%) is DI benefits 

– compression ratio increase and combustion improvements. 
           Energy and Environmental Analysis, Inc. 1‐25   

Figure 1-13. LS 460 and LS430 Fuel Economy Comparison. Contribution of 

Various Engine Technologies. 

Figure 2-14 further compares the fuel consumption improvement of the new engine on 

LS460 versus previous generation 4.3L V8. Fuel efficiency improvements of 6 to 8% 

are available in the mid load area around 800 to 1,500 RPM, as well as at the top load 

area. The map also shows that the new engine was optimized to work with the 8-Speed 

AT, to achieve optimized torque and fuel consumption performance. 
1‐26   Energy and Environmental Analysis

Figure 1-14. Toyota New 4.6L V8 Fuel Consumption Comparison to previous 4.3L 

GM has announced that its DI technology will be extended into V6 engines with first 

application in 3.6L on MY 2007 Cadillac CTS. Further applications are scheduled for 

near future.24

The new engine utilized most DI-related performance advantages for higher power 

rating (up 15%) compared to the previous generation, but also provides 3% better fuel 

economy. The 2007 CTS with its 255-hp, 3.6-liter V-6 is rated at 18 mpg city and 27 

mpg highway (EPA adjusted), which is the same fuel economy as for smaller 2.8L V6, 

also available on this vehicle. 

GM’s 3.6L V6 features dual VVT, which helps reduce exhaust emissions by optimizing 

exhaust valve overlap and eliminating the need for a separate exhaust gas recirculation 

(EGR) system. The injection system operates at 120bar, with lower 35bar used at idle 

conditions. Because of the DI cooling effect, the engine compression ration was 

increased to 11.3. 
           Energy and Environmental Analysis, Inc. 1‐27   

1.5.2 Turbocharged Stoichiometric DISI Engines 

GM is now using a smaller derivative of the Ecotec, 2L I4 SIDI Turbo, in the MY 2007 

Pontiac Solstice GXP (first turbo DISI for GM in North America) and Saturn Sky Red 

Line.25 The engine runs stoichiometric and also features dual VVT. It is tuned to 

produce minimal turbo lag with the use of dual-stroll turbocharger and aggressive valve 

overlap to enhance intake air scavenging for exhaust gases. The result of these and 

other refinements is that the engine develops 260lb-ft torque (a 36% improvement over 

the MPFI turbo version of the engine) over broad range from 2,500 to 5,250 rpm. 

Despite the large increase in power and torque, the engine maintains the fuel 

consumption of a small displacement port injected engine. 

GM has recently reported new estimates concerning the fuel economy improvement 

potential from turbocharged engines under constant performance conditions. Figure 2-

15 summarizes the results of this study. GM’s simulation maintains the baseline vehicle 

(Chevy Equinox with 2.4 natural aspirated PFI) performance and shows that the add-on 

WG (Waste Gated) turbocharger, SIDI and dual VVT can improve fuel consumption on 

FTP cycle by up to 10% relative to an engine with VVT. Up to 20% is possible if this 

technology is combined with the supercharger and mild hybridization. 

Figure 1-15. Fuel Consumption Reduction for Various Boosting Options vs. 

Relative Cost Increases 
1‐28   Energy and Environmental Analysis

Ford already has several direct-injection four-cylinder engines on the market in Europe. 

Mazda markets the 2.3L turbocharged engine in the US on Mazdaspeed6. The de-rated 

power version of the engine with smaller turbocharger is also used on the CX-7 

crossover to provide increased fuel economy.26

Ford has launched the new engine family in the US, called Twin Force, which combines 

direct injection with turbo-charging.27 The 3.5L V6 version was unveiled on the Lincoln 

MKR concept, an E85-capable model. The engine is claimed to perform comparably to, 

or better than V-8 engines, delivering 415 hp (310 kW) and 400 lb-ft (542 Nm) of torque 

on an E85 ethanol blend. 

Ford argues that achieving this type of performance from a V-8 would require an engine 

displacement of 6.0-liter or larger, nearly double the size of the 3.5L. As a result, the 

Lincoln MKR concept delivers 15% better fuel economy than a V-8 with similar 

performance. Ford has indicated that Turbo DISI is likely on ultra-fuel efficient future 

compact cars, such as the Focus. At first, the company was thought to bring a 

European diesel for this platform but the latest information suggests that diesels will be 

reserved for light trucks such as F150, while downsized Turbo-GDI will be the preferred 

alternative for cars with upgraded performance and better fuel economy.28

VW/Audi is known in the US for its direct injection turbo technology based on FSI (Fuel 

Stratified Injection), which is configured to run in stoichiometric mode and marketed on 

wide variety of engines, especially in Europe. VW announced that the FSI technology 

was used to develop the next generation downsized gasoline engine family, called TSI 

(Torque Strong Twincharger). The first products of the family, commercialized in Europe 

on the Golf platform, were 1.4L 125kW and 103kW I4 high performance engines with 

dual charging (supercharger and turbocharger). 

In order to trade the performance for fuel efficiency and decrease the engine costs, VW 

developed a single turbocharger derivative of the TSI engine, a 1.4L 90kW I4.29 Figure 

2-16 provides a pictorial representation of the TSI family development sequence on 

performance versus relative fuel consumption (equivalent to CO2 reduction) scale. The 
           Energy and Environmental Analysis, Inc. 1‐29   

new 1.4L 90kW TSI provides the same performance as a 30% larger 4V FSI (2L natural 

aspirated I4), while providing about 22% improvement in fuel consumption (figure based 

on new Golf equipped with 1.4L TDI and 7-Speed dual clutch transmission compared to 

previous generation Golf – NEDC cycle, at constant vehicle size). 

  

Figure 1-16. VW TSI Engine Relative Performance and Fuel Consumption (CO2 

Reduction). 

Direct injection, VVT and intercooled turbo-charging plus downsizing were the main 

contributors to the fuel efficiency improvement. Further engine improvements include a 

simplified injection system and an optimized turbocharger. The intake manifold was 

simplified to eliminate the tumble flaps, which reduced complexity and costs but still was 

able to achieve good charge mixing. 

When the new 1.4L TSI is compared to 1.6L 85kW FSI, the torque performance results 

are remarkable, with peak torque available across a range from 1,500 to 3,500 rpm (see 

Figure 2-17). 
1‐30   Energy and Environmental Analysis

Figure 1-17. VW New 1.4L Downsized TSI Engine Performance Compared to 1.6L 

FSI. 

Audi has also recently demonstrated that downsized turbocharged DISI engines are 

capable of significant performance improvements. The company started marketing the 

technology with the 2L TFSI introduction and also recently introduced a brand new I4 

1.8L TFSI engine (used in the European Audi A3).30

Figure 2-18 compares Audi A3 performance and fuel consumption with different engine 

options. The new 1.8L TFSI improves fuel consumption by 10% when compared to the 

same size Turbo PFI engine, while offering a 7% increase in rated power. 

  
           Energy and Environmental Analysis, Inc. 1‐31   

Figure 1-18. Audi A3 Acceleration (80 to 120 km/h) and Fuel Consumption 

Comparison among Different Engine Options (European Data). 

1.5.3 FEV Turbo DI, VCR, Flex Fuel Engine Concept 

FEV Engine Technology has showcased a developmental gasoline/E85 turbocharged 

direct injection (GTDI) engine that also features variable compression ratio (VCR) at the 

2007 SAE World Congress. FEV claims that, while offering the potential to generate V-8 

power from a V-6 engine, this concept also provides roughly a 20-25% improvement in 

fuel consumption. 

The system achieves variable compression using an eccentric crankshaft bearing. 

Rotation of the eccentric bearing leads to a vertical position change of the crank train 

relative to the cylinder head and thus, a continuous change in the compression ratio. An 

electric motor controls the adjustment between compression ratios of 8 and 16. 

The VCR engine offers an opportunity to take advantage of the higher octane rating 

available from ethanol fuel by increasing the compression ratio for higher-level ethanol 

blends. Figure 2-19 shows the VCR mechanism and itemizes the estimated fuel 

economy contributions from various technologies.31 According to FEV, DI can increase 
1‐32   Energy and Environmental Analysis

fuel economy of natural aspirated engines by up to 8%. The stratified DI can improve 

fuel economy by up to 18% and Turbo-DISI – by 22%. 

Figure 1-19. FEV VCR Mechanism and Potential Fuel Economy Contributions from 

Various Technologies. 

Although the three principal elements of the engine—VCR, GTDI and Turbocharging—

have been tested on the bench and on the road, FEV has not yet put all three together 

in a vehicle. FEV disclosed that the concept is only a demonstration tool intended to 

show that gasoline engines are able to reach diesel-like efficiencies. 

1.5.4 Spray Guided DISI Lean- Burn Engines 

BMW has publicly stated that the DI stratified combustion provides the greatest 

individual technology step for reducing fuel consumption in SI engines. The company 

chose not to adopt the 1st generation wall-guided DI since its fuel consumption 

advantages were estimated to be comparable to BMW’s Valvetronic CVVLT system. 

However, BMW indicated that the new generation spray-guided DI system eliminates 

the disadvantages of the wall-guided systems, and the company is aggressively 

pursuing it.32
           Energy and Environmental Analysis, Inc. 1‐33   

BMW first launched the technology, dubbed “High Precision Injection and Stratified 

Combustion – HPI”, on 3L I6 twin-turbo engine in the MY 2007 335i sedan. The engine 

is configured with two turbo-chargers, each charging 3 cylinders, which significantly 

reduces turbo lag issues and improves fuel consumption. Each turbo is smaller and 

lighter and has a lower moment of inertia, which allows much faster pressure buildup 

compared to engines with larger single turbo.33

The piezo injection system operates at pressures up to 200bar. The injectors permit up 

to 3 injections per cycle, providing high flexibility for the calibration strategy to supply a 

very efficient combustion with low emissions. The injection system alone improved fuel 

consumption by 2-3% and emissions by 20%, according to BMW. Figure 2-20 provides 

a cutaway view of the new combustion chamber design. Note the injector placed in 

central vertical position with the tip next to the sparkplug electrode. 

Figure 1-20: BMW Spray Guided Stratified HPI Combustion Chamber Cutaway. 
1‐34   Energy and Environmental Analysis

The new engine does not incorporate the Valvetronic system but retains 24-valve 

DOHC cylinder head. The engine tuned for performance on 335i is able to provide 

about 15% performance gain (as measured by 0-100km/h acceleration), which would be 

equivalent to naturally aspirated V8 engine of about 4L displacement (see Figure 2-22). 

BMW has indicated that the HPI optimized for fuel efficiency can achieve a 15 to 20% 

fuel consumption gain, compared to the Valvetronic version of the engine, while still 

providing 5% performance improvement. 

Figure 1-21. Fuel Consumption and Performance of BMW 335i Compared to 

Competition 

(Data is based on European Testing) 

Because of sringent NOx emissions requirements in the US, BMW configured the 

system to run in overall homogeneous mode except during the engine/catalyst warm-up 

periods where the stratified charge is implemented. The same engine is available in 

Europe as a lean-burn stratified charge engine. BMW is expanding the HPI technology 

into naturally aspired engines, including six- and four-cylinder configurations in 

Europe.34 The new 2.0L I4, is scheduled for the 1-Series, and the 3L I6 HPI version for 
           Energy and Environmental Analysis, Inc. 1‐35   

the 5-Series. The engines do retain the dual VVT and variable intake manifold. The 

exhaust emissions control incorporates the NOx storage catalyst. 

Compared to wall-guided stratified DI, the spray-guided system permits a significant 

expansion of the stratified mode on the engine map (see Figure 2-22). The engine 

controller maintains the highly stratified injection mode up to about 4,200RPM and up to 

about 0.5kJ/l specific effective work performed. The stratified envelope is wide enough 

to provide for acceleration of the vehicle up to 160km/h. 

Figure 1-22. BMW New 3L I6 HPI Engine Map, Fuel Consumption and Operating 

Modes. 

Figure 2-23 summarizes the fuel consumption and performance of the new engines 

installed on 1- and 5- Series compared to the predecessors with Valvetronic. The new 

engines reduce fuel consumption on average by 14% and increase power by about 

13%. 
1‐36   Energy and Environmental Analysis

Figure 1-23. Driving performance and fuel consumption for BMW 530i and BMW 

120i with new I6 and I4 engines. 

Mercedes launched its version of spray-guided DISI technology (see Figure 2-24) on 

3.5L V6 engine in MY 2007 CLS350, which is available in Europe. The new engine 

improves fuel consumption by 10% compared to previous version of the V6 under the 

NEDC cycle conditions, while improving power by about 7% and torque 4%.35
           Energy and Environmental Analysis, Inc. 1‐37   

Figure 1-24. Mercedes Spray-Guided DISI Combustion Chamber Design 

The engine features rapid response 200bar piezo injectors and controller by Bosch, 

which opens the nozzle tip outward forming a hollow cone spray pattern.36 The injection 

system can produce multiple injections per cycle which improves the lean burn 

combustion efficiency and reduces noise. The piston bowl was redesigned for this 

process to concentrate the lean mixture in the spark plug area and minimize mixture 

spreading toward outer cylinder walls. 

The engine improvements allowed the lean-burn stratified mode expansion to medium 

loads. Mercedes has shown that at very light loads up to 40% fuel consumption 

improvement is possible with the stratified DISI, although the map window is very 

narrow (see Figure 2-25). As loads increase toward mid-range, fuel consumption 

improvement of 10 to 20% is expected. Overall, the stratified lean burn window is wide 

enough to accelerate the vehicle to speeds of 150km/h. At higher loads the system is 

designed to revert back to stoichiometric mode, at which up to 2% fuel consumption 

improvement is still expected. 
1‐38   Energy and Environmental Analysis

 Figure 1-25. Mercedes Stratified Charge Region Map and Fuel Consumption 

Reduction Potential as Compared to PFI 

The NOx control of the engine is accomplished through high EGR rates (up to 40%) and 

two under-floor LNT (by Umicore – see Figure 2-26). Umicore believes that LNT 

technology is a generally preferrable way to control NOx in lean burn DISI engines. 37

Figure 1-26. Mercedes CLS350 CGI Exhaust System Configuration 
           Energy and Environmental Analysis, Inc. 1‐39   

1.5.5 Direct Injection Summary and Analysis 

The above discussion provides overwhelming evidence that new generation DISI is 

capable to provide a wide range of fuel economy advantages. Stoichiometric DISI is 

already being adopted with incremental fuel economy benefits. Turbo DISI offers an 

opportunity for very large performance increase (at constant displacement) or 

substantial fuel economy gain (downsized engines). Lean burn DISI has reached the 2nd

generation and can achieve very large fuel economy gains, although the aftertreatment 

incremental costs are limiting the technology growth, especially in the US market. 

Table 2-6 summarizes EEA’s earlier estimates for fuel economy gains and costs for 

various DISI technologies. 

Table 1-6. EEA Estimates for Fuel Economy Benefits and Costs for Various DISI 

Technologies. 

All estimates relative to PFI engine with fixed valve timing 

Technology FE Gain [%] $RPE by Engine Configuration 

I4 I6 V6 V8 

Stoich. DI 3.5 (const. 

engine size) 120 155 155 210 

Lean Burn 

DI 

12 (const. 

engine size) 830 (with aftertreatment) 

Turbo -1 (const. 

engine size) 500 560 580 660 

Turbo 7 (engine 

downsized) N/A 

-200 (I6 

replaced by 

I4) 

-200 (V6 

Replaced by 

I4) 

-220 (V8 

replaced by 

V6) 

Turbo 

Stoich. DI 

12 to 14 

(engine 

downsized) 

625 

~0 (V6 is 

replaced by 

I4) 

~0 (V8 

replaced by 

V6) 

Figure 2-27 summarizes equivalent technologies and their potential benefits from 

BMW’s perspective. Using 4-Valve fixed timing/lift PFI engine as the base, the add-on 

stoichiometric DISI (DI λ=1) yields about 5% fuel consumption gain (5% fuel economy) 

with modest power increase (on specific power basis). If the spray-guided DISI is used 

(λ>>1) largely for fuel economy gain, the benefit can reach 20% (25% fuel economy). If 
1‐40   Energy and Environmental Analysis

turbocharged DISI is used without engine downsizing, the engine can maintain fuel 

economy of natural aspirated PFI and the power increase is as high as 50%. BMW’s 

lean burn spray-guided DISI turbocharged technology yields up to 18% fuel 

consumption gain (22% fuel economy) while providing 50% power boost at the same 

time. 

Figure 1-27. BMW Estimates for SI Engine Specific Power and Fuel Consumption 

Reduction Benefits for Various Advanced Technologies. 

Renault has published results of their study, which indicates that engine downsizing with 

turbo-charging can be more cost effective for fuel economy improvement in certain 

vehicle classes, especially compacts, and more attractive than standalone lean-burn DI 

or micro hybridization (see Figure 2-1). Furthermore, the DI Turbo technology fuel 

economy benefits are realized in a wide range of operating conditions. Renault has 

shown that stoichiometric DISI yields about 5% fuel economy gain at constant engine 

size. An estimate for the downsized DISI (stoichiometric) is 17 to 20% fuel consumption 

improvement, which converts to a 21 to 25% fuel economy gain on the NEDC cycle. 

AVL has shown similar results, obtained using computer models. The company used 

VW’s 2L FSI non-turbo engine as the basis for the simulation. Results showed that the 

engine downsizing to 1.4L combined with turbo-charging yields about 11.3% fuel 
           Energy and Environmental Analysis, Inc. 1‐41   

consumption improvement (13% fuel economy). Adding other technologies, such as 

downspeeding (engine torque map shift toward lower RPMs and corresponding 

transmission and axle ratio rebalancing) and cooled EGR can yield about 25% total 

improvement (33% fuel economy). Figure 2-28 summarizes these results. 

Figure 1-28. Fuel Consumption (CO2) Reduction Potential for Various Engine 

Technologies. 

Source: AVL 

Audi has shown that even larger fuel consumption improvements are possible from next 

generation turbocharged DI engines. Figure 2-29 shows fuel consumption and 

performance progression for Audi’s benchmark 2L TFSI used on the A4. When the 

current technology is compared to future 3rd generation expected fuel consumption, the 

engine yields about 25% fuel consumption improvement together with performance 

enhancements. This translates to 33% additional fuel economy improvement over 

Audi’s current TFSI. While details of such large gain are not clear, it is likely the leanburn DISI is necessary together with other drive train improvements. 
1‐42   Energy and Environmental Analysis

Figure 1-29. Audi 2L TFSI Fuel Consumption and Performance Progression. 38

Table 2-7 summarizes fuel economy improvement estimates as reported by various 

sources above. EEA’s recommended fuel economy improvements for these 

technologies are also provided. 

The benefit for turbocharged and downsized DISI engines could be increased slightly as 

a result of new data available from GM and Ford but these estimates are within the 

range we reported earlier, so that the 14 % FE benefit is appropriate. 

EEA recommends that other estimates from earlier analysis should be kept and are 

defensible and perhaps conservative. European engine developers have reported very 

high fuel economy gains for various turbo/DI packages. However, because the data is 

derived against European test cycles, these estimates should be used for reference 

purposes only. 
           Energy and Environmental Analysis, Inc. 1‐43   

Table 1-7. Summary Fuel Economy Gain Estimates for Various DISI Technologies 

and EEA New Recommendations. 

Compared to PFI natural aspirated engine, unless otherwise noted. “Constant performance” condition due 

to engine downsizing can include marginal performance improvement. 

Technology Fuel Economy Gain 

by Source [%] 

Condition EEA Recommended 

Fuel Economy Gain [%] 

Condition 

Lexus 2.5 Compared to 7% Smaller 

Engine 

GM 3 Const. Displacement 

BMW 5 Const. Displacement 

Renault 5 Const. Displacement 

Stoich. DI 

FEV Up to 8 Const. Performance 

3.5 

Constant 

Displacement 

BMW 18 to 25 Downsized Engine, 

compared to Valvetronic 

Constant 

Displacement 

Mercedes 11 Constant Displacement 

Lean Burn DI 

FEV Up to 18 Const. performance 

18 

GM 4 to 9 Const. performance -1 Constant 

Displacement 

Turbo 

AVL 13 Const. performance, 

against base with DI 7 Constant 

Performance 

GM Up to 15 Const. performance, 

includes DVVT 

Constant 

Performance 

Ford 15 Const. performance 

VW 28 Const. performance, with 

double-clutch transm. 

NEDC cycle 

FEV 22 Const. performance 

Turbo Stoich. DI 

Renault 21 to 25 Const. performance 

14 

NEDC cycle 

Concerning add on system costs, EEA obtained new estimates from Bosch (see Figure 

2-4). Table 2-8 below itemizes the Bosch costs and conditions under which the 

estimates were determined. 

Table 1-8. Technology Cost Estimates Derived from Bosch Data. 

All estimates relative to PFI engine with fixed valve timing, unless noted. All estimates at constant 

displacement. Base engine costs: $1,100-I4, $1,600-I6, $1,600-V6, $2,000-V8;$RPE/$Cost Ratio – 1.7 

Technology $RPE by Engine Configuration 

I4 I6 V6 V8 

Stoich. DI 240 350 350 430 

Lean Burn DI 

(with 

aftertreatment) 

820 1,200 1,200 1,500 

Turbo 440 640 640 800 

Turbo Stoich. DI 

with DVVT 770 1,120 1,120 1,400 

Turbo DI with 

engine 

downsize 

700 370(I-6 replaced 

by I-4) 

370 (I-6 replaced 

by I-4) 

600 (V-8 

replaced by V-6) 
1‐44   Energy and Environmental Analysis

1.6 References for Section 2 

                                                                  1

 Energy and Environmental Analysis, Inc., “Technologies to Improve the Fuel Economy 

of Light Duty Trucks to 2015”, Report Prepared for the US Department of Energy and 

the US Department of Transportation, May 2006. 

2

 Y. Boccadoro, L. Kermanac’h, et al., “The New Renault TCE 1.2L Turbocharged 

Gasoline Engine”, Vienna Motor Symposium, April 2007. 

3

 Dr. Klaus Eggerr, “Electronics and Mechatronics Increase Fuel Economy”, Aachen 

Colloquium, Automobile and Engine Technology, October 2006. 

4

 U. D. Grebe, I. Larsson, “Comparison of Charging Systems for Spark Ignition 

Engines”, Vienna Motor Symposium, April 2007. 

5

 Presentation to EEA During Company Visit in 2007. 

6

 T. Arinaga, M. Kobayashi, et al., “A Study of Friction Characteristics of Continuously 

Variable Valve Event and Lift (VEL) System”, SAE Technical Paper 2006-01-0222. 

7

 Nissan Press Release, “NISSAN INTRODUCES INNOVATIVE ENGINE VALVE 

CONTROL TECHNOLOGY - Variable Valve Event & Lift (VVEL) delivers significant 

improvements in dynamic and environmental performance”, March 29, 2007. 

8

 Toyota Press Release, “Toyota Develops Next-generation Engine Valve Mechanism”, 

June 12, 2007. 

9

 “Statement of John German, Manager, Environmental and Energy Analysis, Product 

Regulatory Office, American Honda Motor Company, Inc.”, Before the Senate 

Committee on Energy and Natural Resources, U.S. Senate, January 30, 2007. 

10 Fujii, et al., “Variable Valve Actuating Device”, United States Patent Number 

6,968,819, November 29, 2005. 

11 H. Tagami, Y. Yasui, M. Sato, H. Ito, “Management System for Continuously Variable 

Valve Lift Gasoline Engine”, SAE Technical Paper 2007-01-1200. 

12 R. Flierl, D. Gollasch, A. Knecht, W. Hannibal, “Improvements to a Four Cylinder 

Gasoline Engine Through the Fully Variable Valve Lift and Timing System UniValve®”, 

SAE Technical Paper 2006-01-0223. 
           Energy and Environmental Analysis, Inc. 1‐45   

                                                                                                                                                                                                                    13 Hilite International, “UniValve®, Fully Variable Mechanical Valve Train for Engines”, 

Information Brochure. 

14 M. B. Riley, D.W. Fiddes, “A Fully Variable Mechanical Valvetrain with a Simple 

Moving Pivot”, SAE Technical Paper 2005-01-0770. 

15 AutoWeek, “Valeo Signs up “Several Global Automakers” for Camless Engine”, 

December 18, 2006. 

16 Valeo Technology Description, “Smart Valve Actuation Technology: the Camless 

Engine Becomes a Reality”. Available on the web at: http://www.valeo.com/automotivesupplier/Jahia/lang/en/pid/1317. 

17 D. Durrieu, V. Picron, et al., “Electromagnetic Valve Actuation System: First Steps 

Toward Mass Production”, Variable Valve Control Congress, October 2007, Essen. 

18 H. Katashiba, T. Honda, et al., “Improvement of Center Injection Spray Guided DISI 

Performance”, SAE Technical Paper 2006-01-1001. 

19 H. Toduka, T. Yoshinaga, et al., “Flexible Design of Fuel Injection and Ignition 

Systems for Gasoline Direct Injection Engines”, Vienna Symposium 2006. 

20 W. Bandel, G. Fraidl, et al., “The Turbocharged GDI Engine: Boosted Synergies for 

High Fuel Economy Plus Ultra-Low Emissions”, SAE Technical Paper 2006-01-1266. 

21 G.K. Fraidl, P.E. Kapus, et al., “GDI Turbo: The Next Steps”, Vienna Motor 

Symposium, April 2007. 

22 T. Ueda, Toyota Motor Corporation, “Innovative Development Methodology Based on 

the Toyota Way”, Vienna Motor Symposium, April 2007. 

23 T. Asahi, T. Yamada, H, Hashizume, “The New 4.6L V8 SI Engine for the Lexus 

LS460”, Vienna Motor Symposium, April 2007. 

24 R. Truett, “New Caddy Gets GM’s Most Muscular V-6”, Automotive News, March 26, 

2007. 

25 SAE International Magazine, “Lag Reduced with GM 2.0-L Turbo”, Article, January 

2007 Issue. 

26 SAE International Magazine, “Mazda Expands DISI Turbo to Additional Models”, 

February 2007 Issue. 
1‐46   Energy and Environmental Analysis

                                                                                                                                                                                                                    27 Ford Media, “Lincoln MKR Concept Features New Design Direction”, Available on the 

Web at http://media.ford.com/products/presskit_print.cfm?vehicle_id=1528 

28 R. Truett, “Ford Won’t Offer Diesels in NA Cars”, Automotive News, January 8, 2007. 

29 R. Szengel, H. Middendorf, et al., “The TSI with 90kW – the Expansion of the 

Volkswagen Family of Fuel-efficient Gasoline Engines”, Paper Presented at Vienna 

Symposium 2007. 

30 J. Bohme, W. Hatz, et al., “The New R4 – 1.8L TFSI Engine From Audi”, Aachen 

Colloquium, Automobile and Engine Technology, October 2006. 

31 Publication Media Distributed by FEV at SAE World Congress – 2007, Detroit, 

Michigan. 

32 A. Welter, H. Unger, et al., “The New Turbocharged BMW Six Cylinder Inline Petrol 

Engine”, Aachen Colloquium, Automobile and Engine Technology, October 2006. 

33 C. Luttermann, S. Missy, et al., “High Precision Injection in Combination with 

Turbocharger of the new BMW Twin Turbo Petrol Engine”, Aachen Colloquium, 

Automobile and Engine Technology, October 2006. 

34 P. Langen, T. Melcher, et al., “New BMW Six- and Four-Cylinder Petrol Engines with 

High Precision Injection and Stratified Combustion”, Vienna Motor Symposium, April 

2007. 

35 A. Waltner, G. Vent, et al., “The 2nd Generation of Gasoline-Direct-Injection – Aspects 

of Exhaust Gas Aftertreatment and Catalytic Converter Development”, Aachen 

Colloquium, Automobile and Engine Technology, October 2006. 

36 Bosch Technology Description, “Premiere in the Mercedes-Benz CLS 350 CGI, 

Bosch Gasoline Direct Injection Makes its Debut with Piezo Injectors”, Available on the 

Web at http://www.bosch-presse.de/TBWebDB/en-US/PressText.cfm?id=2625 

37 W. Mueller, S. Eckhoff, S. Philipp, Umicore, “NOx Storage Catalyst Systems for 

Spray-Guided Gasoline Direct Injection Engines”, AutoTechnology Magazine, February 

2007 Issue. 

38 M. Winterkorn, “The Drivetrain Strategies of a Global Company Facing International 

Competition”, Vienna Motor Symposium, April 2007. 
           Energy and Environmental Analysis, Inc. 2‐1   

2 ADVANCED TRANSMISSIONS 

2.1 Introduction 

In both automatic and manual transmissions, increasing the number of gears can 

provide a wider ratio spread between the first and top gears, which allows the engine to 

operate closer to its efficient optimum at a wider variety of vehicle speeds, thereby 

facilitating an increase in fuel economy. Five speed automatic transmissions are 

becoming standard equipment on many vehicles, while 6-speed are in transition from 

luxury to mainstream cars and trucks. 

Table 3-1 summarizes the MY 2005 market penetration data by transmission type and 

OEM. The automotive transmission offerings were highly variable among different 

manufacturers. Honda, for example, offered 5-speed ATs on majority of their cars and 

trucks. GM, on the other hand, made the 5-speed available only on selected models. 

Ford was the leader for 6-speed AT adoption in cars and trucks although the 

penetration was relatively low. 

The manual transmissions in MY 2005 were generally offered by all OEMs, mostly in 

low-end compact cars and trucks. Honda and Nissan stand out with over 10% 

penetration in cars. Ford had substantial penetration of CVTs in both I4 engineequipped cars and trucks, while Nissan is unique because it was the first OEM to use 

the CVT with high output engines (Murano 3.5L V6). 
2‐2   Energy and Environmental Analysis

Table 2-1. MY 2005 Transmission Penetration by Type and OEM. 

 

4sp 

Auto 

5sp 

Auto 

6sp 

Auto 

5sp 

Manual 

6sp 

Manual CVT 

Light Duty Vehicle Penetration 

Daimler 

Chrysler 78.20% 15.70% 4.55% 1.53% 

Ford 59.07% 15.95% 10.37% 9.78% 4.82% 

GM 92.87% 5.77% 0.88% 0.49% 

Honda 23.63% 58.80% 13.23% 4.30% 0.05% 

Nissan 54.65% 33.62% 5.75% 5.98% 

Toyota 42.41% 46.83% 2.34% 7.65% 0.76% 

Light Duty Truck Penetration 

Daimler 

Chrysler 62.18% 34.45% 0.68% 2.69% 

Ford 78.98% 11.06% 0.90% 3.03% 6.03% 

GM 84.10% 14.96% 0.08% 0.85% 

Honda 8.77% 89.02% 2.21% 

Nissan 23.70% 56.10% 1.11% 2.94% 16.16%

Toyota 18.02% 76.90% 2.92% 2.16% 

This section examines the most recent advanced transmission developments and fuel 

economy improvement announcements. EEA’s updated reccomendations for fuel 

economy benefits and costs for new transmissions are also provided. 

2.2 Automatic Transmissions 

2.2.1 Mercedes 7G-Tronic, 7-Speed Automatic Transmission 

Mercedes has marketed their 7-speed AT, 7G-Tronic, since 2004.1

 The transmission 

was derived from a 5-speed AT design with the front single planetary gear set replaced 

by a Ravigneaux planetary gear set with add-on multi-disk brake. The seven speeds 

were achieved by using a total of three planetary gear sets, three clutches and four 

brakes (see Figure 3-1). The transmission is slightly larger than 5-speed but Mercedes 

was able to minimize the weight increase by using a magnesium casing. 
           Energy and Environmental Analysis, Inc. 2‐3   

Figure 2-1. Mercedes 7G-Tronic 

The new transmission was first used by the Mercedes S-Class. Depending on the 

driving cycle, fuel consumption was reported 6.1 to 10.9% lower (fuel economy 

improvement, 6.5 to 12.2%) when compared to 5-speed-equipped vehicle (see Figure 

3-2). In addition to wider gear spread advantage, DaimlerChrysler reported that fuel 

efficiency was improved through improved lubricating fluid, reworked controller and shift 

schedule. The transmission was designed to enable gear skipping during rapid 

downshifting. The torque converter lockup was designed to be active in all forward 

gears. 
2‐4   Energy and Environmental Analysis

17

15.3

11.5

10.1

15.66

14.16

10.79

9.01

0

2

4

6

8

10

12

14

16

18

City Highway Ams-cycle Mot-Cycle

Fuel Consumption [l/100km]

S500L 5-Speed AT

S500L 7-Speed AT

Figure 2-2. Mercedes S500 Fuel Efficiency Comparison, 7G-Tronic vs. 5AT.2

2.2.2 Toyota/Aisin 8-Speed Automatic Transmission 

Toyota/Aisin has developed a new 8-speed automatic transmission commercialized on 

the Lexus LS 460.3, 4 The 8-speed was developed from Aisin’s 6-speed AT which is 

based on a Leppelletier gear set. In order to obtain 8 forward speeds the Leppelletier 

set was connected to a Ravigneaux gear train. The transmission is controlled using four 

multiple clutches, two multiple brakes and one one-way clutch. 

The 8-speed fits in the older 6-speed packaging space. The size performance was 

made possible by smaller components, improved hydraulic circuit design with fewer 

parts and a more efficient geartrain. 

The transmission controller was configured to provide dual clutch-to-clutch shift control 

in which two friction elements engage and two friction elements disengage 

simultaneously for quick and smooth response. The shift speed was improved by 41% 

compared to LS430 6-speed. The transmission can skip two or more speeds on 

downshifts. The ratio spread is quite large, from the first gear’s 4.596:1 to eight’s 

0.685:1, but eight ratios mean they are closely spaced.5
           Energy and Environmental Analysis, Inc. 2‐5   

The transmission was designed to achieve fuel efficiency improvement through the 

following means:6

Extended fuel cut under deceleration. During deceleration the controller can 

command a fuel cut from 5th through 8th gears, including coast-down shift event. 

Higher top gear ratio. Enabled reduction of engine RPMs during highway cruising, 

while the lower gears were optimized for various urban driving conditions. 

Expansion of the neutral control operation range during idle. This is accomplished 

by transmission controller, which brings the turbine speed of the torque converter closer 

to the pump speed (up to 10% fuel economy improvement is possible at idle). 

Expanded lockup. Lockup and flex lock-up control system extended from the 4th to the 

8th gears. 

The result of these improvements is that the 8-speed AT used on Lexus LS460 

improved fuel economy by 6.5% (US combined) compared to 6-speed on older LS 

(comparison at constant 4.6L V8). Also 0-60km/hr acceleration improved by 2%, 100-

180km/hr by 4%. Figure 3-3 summarizes factors that contributed to fuel economy gain 

(note that the gear ratio spread increase contributed about 40% of total gain). 

Figure 2-3. Fuel Economy Improvement, Lexus LS, 8-speed vs. 6-speed. 
2‐6   Energy and Environmental Analysis

2.2.3 ZF 8-Speed Automatic Transmission 

ZF announced development of new 8-Speed AT for passenger cars (see Figure 3-4). 7

The transmission features four planetary gear sets (not Lepelletier though) and five shift 

elements (clutches). Only two shift elements are opened in each gear, which leads to 

considerably lower drag losses. The transmission was also designed to have high total 

gear ratio spread and the torque converter was improved for quick lock-up. 8

Figure 2-4. ZF’s New 8-Speed Automatic Transmission. 

As a result of increased gear ratio spread and additional improvements the new box is 

capable of up to 6% fuel efficiency improvement (6% fuel economy gain), compared to 

the 2nd generation production 6-Speed AT from ZF. When compared to mainstream 5-

speed ATs, ZF claims that their new 8-speed can achieve 14% fuel efficiency 

improvement (16% fuel economy). Figure 3-5 summarizes these claims. 
           Energy and Environmental Analysis, Inc. 2‐7   

Figure 2-5. Fuel Efficiency Improvement for Various ZF Transmission Designs. 

2.3 Automated Manual Transmissions 

Volkswagen has been marketing the 6-speed dual-clutch AMT (Automated Manual 

Transmission –DSG®) since 2003. The transmission has an input torque capacity of 

350 N-m, and is used in compact and mid-size vehicles, such as the Golf and Passat. 

VW has announced that a brand new transmission was developed for the DSG® AMT 

family, a 7-Speed AMT (see Figure 3-6). The transmission has a torque capacity of 250 

N-m, so it will be used in lower power versions of the Golf/Passat but also in 

subcompacts such as the Polo.9

In addition to a higher gear ratio spread, the new transmission features a ”dry” clutch 

design (hence the reduced torque capacity). The new clutch reduces internal losses 

substantially since the cooling oil drag is eliminated. Other reported design benefits 

include: 

• Gear ratio change for better drive-off performance and cruising; 

• Decreased controller power consumption; 

• Increased mechanical transmission efficiency. 
2‐8   Energy and Environmental Analysis

Figure 2-6. Cross Section of New 7-speed AMT from VW. 

The new 7-speed AMT achieved substantial fuel efficiency improvement even 

compared to the already competitive 6-speed AMT. Figure 3-7 summarizes this data 

and compares various transmission designs against the 6-speed manual transmission 

baseline. The data shows that, under NEDC cycle conditions, the 6-speed AT fuel 

consumption is 5 to 15% higher when compared to 6-speed manual transmission. The 

6-speed AMT fuel consumption performance is basically the same as the manual 

transmission, although under certain conditions, the AMT can achieve 5% fuel 

consumption reduction but also up to 3% penalty can be realized. The new 7-speed 

AMT is claimed to have fuel consumption advantage across the board, 7 to 12% better 

than the 6-speed manual. 
           Energy and Environmental Analysis, Inc. 2‐9   

Figure 2-7. Fuel Consumption Comparison of Different Transmission Designs 

from VW. 

MQ250 - 6-speed Manual Transmission; 

AQ – 6-speed Automatic Transmission; 

DQ250- 6-speed AMT; 

DQ200 – 7-speed AMT. 

Cost estimates for the new transmission are not publicly available but the fact that its 

application is targeted for subcompacts such as Polo suggest that the costs must be 

competitive with the older 6-speed AMT. By eliminating the clutch cooling oil circuit, VW 

removed parts such as suction filter, oil cooler and pressure lines. Also the dry clutch 

design allowed decreased transmission oil requirements from 7 to 1.7L. The shift 

mechanism was simplified so that 7 speeds can be controlled with four actuators. The 

result of these modifications is that the 7-speed AMT weight decreased to 73kg 

(compared to 80kg for 6-speed AMT). Also transmission size was substantially reduced. 

2.4 Continuously Variable Transmissions 

Continuously Variable Transmissions (CVT) have been in mass production for many 

years and have reached mainstream status. About 2.5 million CVTs, mainly 

compression belt drive-type, have been produced in 2006 worldwide. Nissan, Toyota 

and DaimlerChrysler are leading automakers that adopted the technology on many 

models. 
2‐10   Energy and Environmental Analysis

The fuel economy performance for CVTs is generally competitive with manual 

transmissions. In some cases, up to 5% benefit has been demonstrated when 

compared to manual transmissions.10 Compared to 4-speed automatic transmissions, 

up to 15% fuel economy benefit can be realized.11

Bosch has shown that there is a lot of potential for further CVT technology improvement 

(see Figure 3-8) . Improvements can be derived from refined electronic controls that can 

minimize losses in the oil pump, torque converter, variator and drive/neutral/reverse 

unit. The company has shown that up to 7.5% additional fuel economy improvement is 

possible in FTP cycle with these strategies. Also, advanced CVTs would be well suited 

for mild hybridization, since electrical oil pump would allow engine shutdown. With startstop technology implementation fuel economy improvement can further increase to 

9.5%. 

Figure 2-8. Bosch CVT Technology Expected Fuel Efficiency Improvements. 

Baseline for comparison is current CVT technology used in A-Class subcompact with 180N-m torque 

capacity 1.9L I4 engine. 

M- Measured Values; S- Simulation. 

2.5 Advanced Transmission Summary and Analysis 

EEA’s earlier estimates for advanced transmission fuel economy improvements and 

costs (converted to $RPE) are summarized in Table 3-2. EEA has also documented that 

RPE increase for each additional gear is about $50. 
           Energy and Environmental Analysis, Inc. 2‐11   

Table 2-2. EEA Earlier Estimates for Fuel Economy Benefits and RPE Increase, 

Compared to 4-Speed AT 

Transmission Type Fuel Economy Benefit [%] $RPE 

5-Speed AT 2.5 200 

6-Speed AT 4.5 205 

7-Speed AT 5.3 255 

AMT 7.0 210 

CVT (engines <2.8L) 

CVT (engines >2.8L) 

7.5 

6.0 

240 

380 

The new information suggests that the benfit for 7-speed and 8-speed transmissions 

should be higher than originally estimated by EEA. Mercedes reported that lower-end 

fuel economy gain, 5-speed AT versus the 7G-Tronic, is about 6.5%. EEA’s information 

in Table 3-1 above indicates that 5-speed versus 7-speed fuel economy gain is 2.8%, 

which is the benefit for a wider gear ratio spread and additional speeds, isolated from 

other possible transmission refinements. Mercedes fuel economy gain does include 

other transmission improvements, such as improved lubricating oil, reworked controller 

and lockup schedule, etc. 

Lexus information (see Figure 3-3) indicates that the gear ratio spread increase with two 

additional gears contributes about 40% of the total fuel economy gain. When Mercedes’ 

6.5% figure is multiplied by 0.4, the result is 2.6%, which is very consistent with EEA’s 

estimate of 2.8%. Therefore, the fuel economy benefits for gear increases from 5 to 7 

speeds in Table 3.1 appears to not include further increases in ratio spread. 

The 8-Speed AT fuel economy benefits are documented by Toyota/Aisin. Once again, 

the gear ratio spread increase of two gears (8-speed versus 6-speed) contributed about 

2.6% (0.4 x 6.5%) of fuel economy gain. Other fuel economy gains for Toyota’s design 

were associated with a new controller, which achieves additional fuel economy benefits 

at idling, a reworked torque converter and an expanded fuel-cut envelope. 
2‐12   Energy and Environmental Analysis

When EEA’s 6-speed versus 7-speed fuel economy incremental benefit of 0.8% is 

subtracted, the 8-speed versus 7-speed the remaining benefit is 1.8%. EEA believes 

that this fuel economy figure is reasonable for the 8-speed’s incremental FE gain over a 

7-speed. It also should be noted that other transmission improvements could provide an 

additional 1.5 to 2 % benefit over current transmissions. 

ZF’s fuel consumption figures (see Figure 3.5) for various transmissions were 

developed in Europe and generally provide more aggressive gains, especially 5-speed 

versus 2nd generation 6-speed AT. ZF data does not appear to be representative of the 

US test cycles but certainly supports arguments that substantial fuel economy benefits 

can be obtained with fully optimized advanced transmissions with a wide gear ratio 

spread, as long as internal transmission losses are properly managed. 

VW’s information for AMT developments illustrates that 6-speed AMT provides a fuel 

consumption benefit of 2 to 10% when compared to 6-speed AT, although the data was 

developed in Europe and is highly dependent on driving conditions. EEA’s fuel economy 

benefit, AMT versus 6-speed AT in table 3-1 is 2.5%, and falls within VW’s range. More 

importantly, VW has shown that further AMT speed number increase can result in an 

additional fuel efficiency benefit of up to 10% (7-speed versus 6-speed AMT). While this 

large benefit is yet to be demonstrated under FTP conditions, EEA feels that AMT 

separation into discreet 6-speed AMT and 7-speed AMT technologies might be 

warranted. The discussion above indicates that 6-speed versus 7-speed automatic 

transmission fuel economy difference is 0.8%. EEA expects that similar AMT speed 

number increase should deliver at least a similar benefit due to gear ratio spread 

increase. More precise fuel economy difference should be confirmed when these new 

transmission models are introduced in the US market. 

For CVTs, the EPA FTP fuel economy data supports the fact that these transmissions 

can achieve comparable fuel economy performance versus models equipped with 

manual transmissions. When CVT is compared to a less efficient 4-speed AT, 

substantial fuel economy benefits can be realized. 
           Energy and Environmental Analysis, Inc. 2‐13   

Table 3-3 compares selected MY 2007 Nissan models equipped with CVT against 

comparable models with either automatic or manual transmission. One model, the 

Nissan Versa, is sold in trim levels with either CVT or 4-speed AT with otherwise 

identical specifications. Despite the CVT-equipped model being slightly heavier, a fuel 

economy benefit of 5% is realized compared to 4-speed AT. Other models in Nissan’s 

lineup do not have comparable AT counterparts, but CVT comparison against various 

manuals indicate competitive performance in most cases. 

Table 2-3. MY 2007 Vehicle Fuel Economy Comparison, CVT vs. 4-speed AT or 

Manual 

All vehicles are FWD; Fuel Economy is EPA Combined Unadjusted. 

MODEL Engine Curb Weigh [lbs] Transmission 

EPA Fuel 

Economy 

[mpg] 

Percent 

Difference 

NISSAN VERSA 1.8L I4 2779 CVT 37.7 

NISSAN VERSA 1.8L I4 2749 Auto(L4) 35.9 5.0 

 

NISSAN SENTRA 2L I4 2897 CVT 37.1 

NISSAN SENTRA 2L I4 2853 Manual(M6) 35.8 3.6 

NISSAN ALTIMA 2.5L I4 3142 CVT 34.3 

NISSAN ALTIMA 2.5L I4 3093 Manual(M6) 35.0 -1.9 

NISSAN ALTIMA 3.5L V6 3334 CVT 28.6 

NISSAN ALTIMA 3.5L V6 3268 Manual(M6) 28.2 1.5 

Bosch information discussed above indicates that substantial CVT improvements are 

possible in the future. Therefore, EEA’s slightly higher fuel economy benefits for CVT in 

Table 3-1 are defensible, if not conservative, and should continue to be used. 

Concerning the new transmission costs, EEA has received no new information to 

update the cost data. The 8-Speed AT design add-on RPE (above 4-Speed AT) can be 

estimated to be about $320 (270$ for 7-Speed plus $50 for an additional gear). 
2‐14   Energy and Environmental Analysis

2.6 References for Section 3 

                                                                  1

 DaimlerChrysler Press Release, “7G-Tronic: Mercedes Benz Presents the World’s 

First Seven-speed Automatic Transmission for Passenger Cars”, May 14, 2003. 

2

 J. Greiner, C. Doerr, H. Nauerz, M. Graeve, “The New “7G-Tronic” of Mercedes-Benz: 

Innovative Transmission Technology for Better Driving Performance, Comfort and Fuel 

Economy”, SAE Technical Paper 2004-01-0649. 

3

 Automotive Engineering International Magazine, “Lexus LS460: AEI Best Engineered 

Vehicle, 2007”, April 2007 Issue. 

4

 Aisin AW Co., LTD., Informational Brochure “Driving Innovation”, Distributed at SAE 

World Congress, 2007. 

5

 M. Kondo, Y. Hasegawa, et al., “Toyota AA80E 8-Speed Automatic Transmission with 

Novel Powertrain Control System”, SAE Technical Paper 2007-01-1311. 

6

 H. Ota, K. Nozaki, et al., “Toyota’s World First 8-Speed Automatic Transmission for 

Passenger Cars”, SAE Technical Paper 2007-01-1101. 

7

 ZF Press Release, “ZF Develops Automatic 8-Speed Transmission for Passenger 

Cars”, May 2, 2007. 

8

 L. Brooke, SAE International Magazine, “Six, Seven, Eight – the Great Gear Debate”, 

Article in June 2007 Issue. 

9

 F. Rudolph, M. Schafer, at al., “The Innovative Seven Speed Dual Clutch Gearbox for 

Volkswagen’s Compact Cars”, Vienna Motor Symposium, April 2007. 

10 Prof. Nick Vaughan, “CVT Opportunity”, AutoTechnology, February 2007. 

11 F. Sluis, T. Dongen, et al., “Efficiency Optimization of the Pushbelt CVT”, SAE 

Technical Paper 2007-01-1457. 
           Energy and Environmental Analysis, Inc. 3‐1   

3 DIESEL AND HYBRID UPDATE 

3.1 Light Duty Diesels 

New generation, DPF-equipped light duty diesels (Tier 2 Bin 8) are currently sold in the 

US by DaimlerChrysler and VW and a major expansion of diesel models is expected in 

the near future. Audi, BMW, Honda, VW have announced they will offer the Bin 5-

compliant light-duty diesel cars by the end of this decade. Other OEMs, such as GM, 

Ford and Nissan, are planning diesel light duty trucks and SUVs starting in MY 2009.1

New European data confirms that diesels typically offer about 40% improvement in fuel 

economy compared to gasoline engines on competitive performance basis.2

Interestingly, the diesel fuel economy advantage increases with the increased vehicle 

weight (see Figure 4-1 from Ford). This is due to the fact that diesels offer very high 

torque and for larger vehicles such as trucks and SUVs, which are designed for towing 

and off-road capability, gasoline engines must offer very large displacement to compete 

with diesels. 

Figure 3-1. Diesel Comparison versus Gasoline by Vehicle Weight, . 

European Data. Diesel vs. Gasoline CO2 Difference is from 20 to 25%. 
3‐2   Energy and Environmental Analysis

This section examines a few diesel technology development examples and associated 

fuel economy improvement opportunities. EEA’s updated analysis is also provided. 

3.1.1 Diesel Technology Advances 

Diesel engines are experiencing unprecedented development in Europe as auto 

manufacturers are adjusting their power train strategies to deal with the EU CO2 

regulations and emission standard changes. These new technologies are expected in 

the US market. Two recent examples by BMW and Honda illustrate the magnitude of 

these new developments. 

BMW has announced that one of their mainstream diesel engines in Europe, the 2.0L l4 

was redesigned and achieved yet another increase in fuel efficiency and performance 

gains. This engine is used in wide variety of products including the 5-Series and X3.3

The new engine version was completely redesigned with major areas of improvement, 

compared to the previous generation engine, as follows: 

• Friction and mass reduction of parts such as crankshaft bearings, high pressure 

injection pump; 

• Adoption of aluminum crankcase; 

• Adoption of 1,800bar piezo CR injection system; 

• New high pressure pump with 20% lower power consumption; 

• New variable geometry turbocharger, EGR and ECU; 

• New A/C compressor with clutch 

As shown on the engine map in Figure 4-2, the above measures resulted in fuel 

consumption improvement of up to 10% (against previous generation 2L diesel). While 

10% improvement is limited to small area of the map, the 4 to 8% improvement is 

realized under most conditions. 
           Energy and Environmental Analysis, Inc. 3‐3   

Figure 3-2. Fuel Consumption Improvement of BMW’s New 2.0L Diesel Compared 

to the Previous Generation. 

The new engine was specifically designed to work with mild-hybridization, i.e. engine 

start-stop control and intelligent alternator control. The intelligent alternator is designed 

to generate electrical power when the vehicle is in overrun during braking, while the 

stop-start function shuts down the engine during prolonged idling. With such steps BMW 

reported that fuel efficiency was further increased up to 15%. The comparison is for the 

European 1-Series, which adopted the technology in MY 2007.5 (see Figure 4-3 below). 

BMW indicated that the new engine will be used on the 3-Series and other appropriate 

platforms. 

The exhaust emissions of the vehicle are controlled by closed-coupled DOC/DPF 

system (SiC catalyzed-type), which is integrated into one housing. The closed-coupled 

position maintains catalyst and filter temperatures above 600°C under most conditions 

so regeneration is continuous with minimal post-heating requirements. 
3‐4   Energy and Environmental Analysis

Figure 3-3. Fuel Consumption and Performance of New BMW 1-Series Diesel 

Compared to Previous Generation Diesel Vehicles. 

Honda has announced that the European diesel technology will be modified for the US 

market and will be able to meet the Tier 2 Bin 5 emissions requirements.4 The market 

entry is expected in 2009. Figure 4-4 summarizes the new engine and exhaust after 

treatment configuration. In addition to the latest piezo CR injectors, the engine will use 

closed-loop cylinder pressure sensors to control combustion. The closed-coupled DOC 

and DPF, as well as the under-floor NOx trap system, will be used for after treatment. 

Figure 3-4. Honda Diesel Technology for the US Market. 
           Energy and Environmental Analysis, Inc. 3‐5   

3.1.2 Diesel Exhaust After treatment to Reach Bin 5 

The latest announcements indicate that, in near term, light duty diesels in the US are 

expected to utilize two exhaust system configurations in order to reach the Tier 2 Bin5 

(CA LEV II LEV) standards. The first is DPF and Urea-SCR catalyst combination, the 

second, is a LNT (Lean NOx Trap) and DPF system. Figure 4-5 illustrates the basic 

layouts of the two approaches. 

Figure 3-5. Basic Configurations for Urea-SCR and LNT-based Diesel After 

treatment. 

AVL has shown that the after treatment selection costs can be modeled as a function of 

engine size.5 Since the LNT construction requires precious metals, its costs are 

expected to scale with the engine displacement (i.e., engine-out gas volume). The SCR 

system, on the other hand, does not require precious metal support, so costs are 

dominated by extra hardware for urea dosing, storage and injection. Figure 4-6 

illustrates that a tradeoff exists between these dominant costs. According to AVL, the 

break-even is about 1.6L engine size. 

The AVL data likely reflects the Euro IV-level diesel engine-out emissions in Europe. As 

illustrated above, automakers are redesigning their engines to achieve additional 

engine-out reductions. As a result, the break even point for LNT versus SCR solutions 

will likely move toward engine size of around 2.4L, as illustrated by Honda 

announcements (their first engine in the US market will be 2.2L or slightly larger). 
3‐6   Energy and Environmental Analysis

Figure 3-6. Relative Cost Comparison between Lean NOx Trap (LNT) and UreaSCR Catalysts. 

Assumptions: 

SCR Catalyst and LNT volumes are 1.5 times the engine displacement; precious metal loading for LNT: 

100g/ft3, Costs include sensors and wiring harnesses. 

3.1.3 Diesel Summary and Analysis 

EEA has documented that a light duty diesel provides about 35% fuel economy 

advantage when compared to gasoline engines. Table 4-1 summarizes this information, 

including the expected $RPE increase, for I4 and V6 engines. 

Table 3-1. Light Duty Diesel Fuel Economy Improvement and $RPE Increase. 

RPE increase is for technologies needed to certify diesels at Tier 2 Bin 5 emissions. 2015+ RPE assumes 

PCCI/HCCI.

 Fuel Economy 

Benefit [%] 

Incremental $RPE Notes 

I4 Engine 35 + 3 

2,200 near term 

2,000 (2015+) 

Compared to 

gasoline I4, includes 

after treatment 

V6 Engine 35 + 3 

3,200 near term 

3,000 (2015+) 

Compared to 

gasoline V6, 

w/aftertreatment 
           Energy and Environmental Analysis, Inc. 3‐7   

Since the new generation diesels equipped with DPFs are available in the US, albeit 

mostly in the luxury segment, EEA has analyzed the available models for fuel economy 

benefit compared to similar conventional gasoline models. Table 4-2 summarizes this 

analysis for new diesels introduced in MY 2007 by DaimlerChrysler, on constant 

displacement basis. Since the same displacement gasoline engines are not marketed 

by DaimlerChrysler, other OEM models in the same size class are used. As a result, 

this comparison method should be used for reference purposes only since wide range 

of differences exist among different OEM powertrain configurations. 

The constant displacement analysis shows that FTP diesel fuel economy advantage 

against gasoline is highly variable. One model, the Mercedes E320 Bluetec, has a 

gasoline competitor, the Jaguar S-type, with comparable specifications, including 

reasonably close curb weight. The Jaguar is tuned for high performance (hence 

premium gasoline is required) but the diesel still provides 33% advantage (adjusted for 

transmission difference). Another model, the Mercedes ML320 SUV is comparable to 

the BMW X5, although the ML320 is equipped with 7-speed automatic. The fuel 

economy increase in this case is about 20%, if the difference is adjusted for 

transmission advantage. The Jeep Grand Cherokee provides only 10% advantage but 

the comparison is against the premium X5 so the constant engine displacement 

comparison is not really useful in this case. 
3‐8   Energy and Environmental Analysis

Table 3‐2. MY 2007 LD Diesel Fuel Economy Comparison against Gasoline Models on Equal

Displacement Basis.

Fuels Indicated: D-Diesel, P-Premium Unleaded, R-Regular Unleaded 

FE – Fuel Economy, EPA Combined Unadjusted 

MODEL Engine TRANS DRIVE

FE 

[MPG]

FE 

Diff.

[%] 

Rated 

Power

[hp] 

Rated 

Torque 

[ft-lbs] 

Power 

and 

Torque 

Ratio 

Average

CURB 

WEIGHT

[lbs] 

MERCEDES E320D 3L V6 Auto(L7) R 34.7 208 388 3860

JAGUAR S-TYPE 3.0L 3L V6 Auto(L6) R 25.9 34.0 235 216 1.34 3760

 

JEEP GRAND CHEROKEE 3L V6 Auto(L5) 4 25.1 215 376 4691

BMW X5 3.0SI 3L I6 Auto(S6) 4 22.8 10.0 260 225 1.24 4982

MERCEDES GL320 CDI 3L V6 Auto(L7) 4 26.1 215 398 5296

BMW X5 3.0SI 3L I6 Auto(S6) 4 22.8 14.5 260 225 1.29 4982

MERCEDES ML320 CDI 3L V6 Auto(L7) 4 27.5 215 398 4817

BMW X5 3.0SI 3L I6 Auto(S6) 4 22.8 20.6 260 225 1.29 4982

MERCEDES R320 CDI 3L V6 Auto(L7) 4 28.2 215 398 5092

BMW X5 3.0SI 3L I6 Auto(S6) 4 22.8 23.7 260 225 1.29 4982

The data in Table 4-2 data indicates that diesel engines provide substantial 

performance advantage, if compared on constant displacement basis. Even though 

diesels do have somewhat lower power ratings, the torque advantage is very large. As a 

result it was necessary to compare the MY 2007 diesels against gasoline counterparts 

on performance basis. 

The performance method allows the diesel option comparison within the same model 

family, including reasonably close weight specifications and identical transmissions. 

Table 4-3 summarizes the model choices for this analysis, including rated power and 

torque specifications. Note that, when the power and torque rating ratios for diesel and 

gasoline models are averaged, the results fall reasonably close to unity (from 1.07 to 

1.17). While the comparison can not be considered to provide a “constant performance” 

basis, the data is reasonably consistent to draw conclusions. 
           Energy and Environmental Analysis, Inc. 3‐9   

The analysis shows that fuel economy advantage for US diesels, at competitive 

performance, also varies although the spread is relatively narrow from about 26% to 

38%. Three models, the Mercedes E320/R320 and Jeep Grand Cherokee 2WD, do 

show fuel economy advantage for diesels in the range of EEA estimates in Table 4-1. 

Table 3-3. MY 2007 LD Diesel Fuel Economy Comparison against Gasoline Models 

on “Competitive Performance” Basis. 

Fuels Indicated: D-Diesel, P-Premium Unleaded, R-Regular Unleaded 

FE – Fuel Economy, EPA Combined Unadjusted 

MODEL Engine TRANS DRIVE

FE

[MPG]

FE 

Diff. 

[%] 

Rated 

Power 

[hp] 

Rated 

Torque 

[lb-ft] 

Power 

and 

Torque 

Ratio 

Average

CURB

WEIGHT

[lbs]

MERCEDES E320 CDI 3L V6 Auto(L7) R 34.7 208 388 1.14 3860

MERCEDES E350 3.5L V6 Auto(L7) R 25.1 38.3 268 258 3740

 

GRAND CHEROKEE 3L V6 Auto(L5) R 26.0 215 376 1.07 4460

GRAND CHEROKEE 4.7L V8 Auto(L5) R 19.7 31.9 235 305 4421

GRAND CHEROKEE 3L V6 Auto(L5) 4 25.1 215 376 1.07 4692

GRAND CHEROKEE 4.7L V8 Auto(L5) 4 19.8 26.8 235 305 4691

MERCEDES ML320 CDI 3L V6 Auto(L7) 4 27.5 215 398 1.17 4817

MERCEDES ML350 4MATIC 3.5L V6 Auto(L7) 4 21.8 26.4 268 258 4705

MERCEDES R320 CDI 3L V6 Auto(L7) 4 28.2 215 398 1.17 5092

MERCEDES R350 3.5L V6 Auto(L7) 4 21.3 32.6 268 258 4938

The Jeep Grand Cherokee Limited offers the diesel engine option for a $3,050 price 

premium. Mercedes diesel models are available with diesel engines at a $1,000 price 

premium. Both Mercedes and Jeep offer the same 3L V6 diesel engine, so the current 

MSRP diesel premium figures should be used for reference purpose only, illustrating the 

current OEM pricing strategies. 

Mercedes and Jeep diesel models are equipped with DPFs and LNT-type aftertreatment 

but NOx conversion efficiency is not high enough so these vehicles are certified to Bin 

8. The add-on technologies will be required to bring these diesels into the Bin 5 

compliance. Mercedes announced that the Urea-SCR will be used for next generation 

diesels (Bluetec II). While more research is needed to update the expected costs for 
3‐10   Energy and Environmental Analysis

different NOx control solutions, EEA feels that the cost estimates listed in Table 4-1 are 

defensible and should continue to be used for the Bin 5-level diesel technology. 

The diesel technology development examples in previous sections do provide evidence 

that next generation diesels in the US will have an opportunity for higher fuel economy 

benefit. Therefore the Table 4-1 fuel economy estimates should also be considered 

valid, on equal performance basis. 

3.2 Hybrid Technology 

3.2.1 General Hybrid Product Trends 

Toyota and Honda have established an early lead in the hybrid market. Honda hybrid 

technology represents the 2nd generation of development, with significant improvements 

reported for all hybrid components (see Figure 4-7). Honda has announced that the next 

step in hybrid vehicle development will be the introduction of an all-new hybrid car to be 

launched in the US in 2009.6

 This new hybrid vehicle will be a dedicated, hybrid-only, 

model with a target price lower than the current Civic Hybrid. The projected annual 

sales volumes in North America will be about 100,000 units. 

Figure 3-7. Honda Civic HEV 2nd Generation Technology Improvements. 
           Energy and Environmental Analysis, Inc. 3‐11   

Current Toyota HEVs also represent 2nd generation hybrid technology. Toyota’s key 

hybrid componentry, such as Power Control Unit (PCU), was reported to achieve 

dramatic power density increase, and likely had associated cost reductions with each 

new model introduction (see Figure 4-8).7

 

Toyota has announced that the THS (Toyota Hybrid System) architecture would be 

expanded to virtually every mainstream nameplate with worldwide sales volumes 

projected to approach 1 million units/year by early next decade. The company has 

hinted that the cost premium for hybrids would be “halved” compared to current hybrids. 

0

1

2

3

4

5

6

MY 2004 MY 2005 MY 2006 MY 2007

Relative Power Density

Figure 3-8. Toyota Hybrid Power Control Unit Relative Power Density Increase, 

MYs 2004-2007. 

MY 2004 is PCU performance for the Prius II, MY 2007 – Lexus LS600h 

GM is responding with a aggressive HEV strategy and will market at least 12 models in 

high volume car and truck lines by 2010 (see Figure 4-9). GM’s first BAS (Belt 

Alternator Starter) mild hybrid system, used on the Saturn Vue, was designed to 

improve fuel economy by up to 20% without sacrificing performance. The TMH (Two 

Mode Hybrid) system is expected to deliver a minimum 25% improvement in trucks and 
3‐12   Energy and Environmental Analysis

SUVs. The TMH application on the Saturn Vue will deliver up to 45% fuel economy 

improvement over the current base Vue. 

GM has announced that the Saturn Vue TMH will also be capable of being driven in 

limited electric-only mode (i.e., PHEV- Plug-in Hybrid configuration), assuming that the 

Lithium-Ion battery packs materialize, as anticipated.8

 Even more advanced PHEV 

architecture is planned, once again subject to LiI technology development, in the form of 

Chevy Volt concept with a target all-electric range of 40 miles. 

Figure 3-9. GM Hybrid Product Plan. 

Source: GM9

Ford announced that MY2008 Escape was refreshed with new exterior panels and 

refined interior. The new Escape Hybrid carries an EPA rating (using the new reporting 

system) of 34 mpg city, 30 mpg highway, 32 mpg combined. The 2007 Escape Hybrid 

has a rating (adjusted using the new system) of 31 mpg city, 29 mpg highway, and 30 
           Energy and Environmental Analysis, Inc. 3‐13   

mpg combined. Based on these figures, fuel economy performance increased 10%, 

3%, and 7% for city, highway and combined, respectively. 

Ford reported that these large fuel economy gains were possible through revisions to 

the ECU software and hybrid electronics, which improved transition between gasoline 

and electric operation. Also, the regenerative brakes were reworked for better feel and 

efficiency. A new Electric Power Assist Steering (EPAS) was also implemented. 

3.2.2 Supplier Announcements 

Valeo is known for its mild hybridization technology developed in Europe called 

StARS.10 The system is relatively simple and its main component is a belt-driven 

starter/generator controlled by separate power electronics. The StARS is able to provide 

start-stop function, regenerative braking and some torque assistance. The system 

operates at conventional 12V voltage, although regenerative braking-capable system 

requires additional power storage through EDLC. DC/DC converter is used to provide 

floating system voltage up to 24V. The torque assist system is capable to provide up to 

4kW additional power. 

Valeo has shown that, depending on the system’s functionality, mild-hybridization can 

provide up to 20% fuel economy benefit (see Figure 4-10). The company claims that 

under real city congested driving conditions (based on testing in Paris, France), the 

start-stop function alone can provide up to 25% fuel economy benefit (officially NEDC 

benefit is 6%). 
3‐14   Energy and Environmental Analysis

Figure 3-10. Valeo StARS Strategy and Fuel Economy Benefits. 

Siemens VDO published results of the fuel efficiency improvement potential analysis for 

various hybrid technologies. 11 Their data is summarized in Table 4-4 and converted to 

fuel economy improvement potential. Base vehicle conditions were not clearly defined 

by Siemens but their data illustrates that very large fuel economy gains, 33 to 77%, are 

possible with fully optimized hybrids depending on the test cycle conditions. Mild 

hybridization can yield more than 18% fuel economy improvement. 

Table 3-4. Fuel Economy Improvement Potential of Various Hybrid Technologies. 

Source: Siemens VDO 

Add On Technology 

Consumption 

[l/100km] 

Cumulative 

Consumption 

Improvement 

[%] 

Fuel 

Economy 

Improvement 

[%] 

Base 9.17 

Optimized IC Engine and 6-speed Transmission 8.33 9.2 10.1

Integrated Starter Generator (ISG) 8.06 12.1 13.8

Start-Stop Operation 7.57 17.4 21.2

Regenerative Braking with Adoptive Shifting 

Strategy 6.49 29.2 41.2

Electric Launch 5.92 35.4 54.8

Electric Drive 5.29 42.3 73.3

Optimized Accessories 5.18 43.5 77.0
           Energy and Environmental Analysis, Inc. 3‐15   

3.2.3 Summary and Analysis 

EEA previous estimates for fuel economy and RPE increase for various hybrid 

packages are summarized in Table 4-5 below. 

Table 3-5. Hybridization RPE Increase and Fuel Economy Benefits 

RPE at high sales volume, effects of learning and technology simulated. 

 

Technology 2005 2010 2015 

BAS Hybrid Component RPE [$] 950 800 660 

BAS FE Benefit [%] 8 8 9 

IMA Hybrid Component RPE [$] 2,950 2,525 2,100 

IMA System FE Benefit [%] 51. 53 56 

2 motor Hybrid Component RPE [$] 4,500 3,900 3,300 

2- motor Hybrid System FE Benefit [%] 60 65 70 

Since the technology has reached mass production volumes, the EPA FTP testing data 

can be used to confirm the fuel economy advantage trends for hybrids. The first set of 

data, presented in Table 4-6, specifies the MY 2007 hybrid vehicles and compares their 

fuel economy and other parameters against vehicles in the same size class on an equal 

displacement basis. Note that Toyota Prius and Honda Civic HEVs are equipped with 

unique downsized engines, which are not available in the US conventional vehicles. 

When the Prius and Civic, a well as the Lexus 450h (which is more than 600lbs heavier 

than comparable vehicles with the same engine size), are excluded from the analysis, 

fuel economy difference is relatively consistent among many hybrid models and 

averages about 12% for mild hybrids (Aura and Vue) and 40% for full 2-motor hybrids. 

The Honda HEVs are only models with the IMA-type single motor system. The Accord 

HEV provides a 32.5% fuel economy advantage compared to the conventional 3L V6 

Accord. 
3‐16   Energy and Environmental Analysis

Table 3-6. MY 2007 Hybrid Vehicle Fuel Economy, Key Specification and MSRP 

Comparison on Constant Displacement Basis. FE – Fuel Economy – EPA Combined Unadjusted; 

*-Honda Civic and Toyota Prius HEVs do not have “Equal Engine Displacement” Counterparts. 

**-Conventional Saturn Vue does not have the 2.4L option (2.2L I4 is the standard engine). 

MFR CAR LINE DISP CYL TRANS DRIVE 

Fuel 

Economy 

 [mpg] 

FE Diff. 

[%] 

Curb 

Weight

 [lbs] 

Mild (BAS) Hybrid Comparison

SATURN AURA HYBRID 2.4 4 Auto(L4) F 35.7 3529

CHRYSLER SEBRING 2.4 4 Auto(L4) F 32.0 11.6 3287

TOYOTA CAMRY 2.4 4 Auto(L5) F 31.9 11.8 3307

 

SATURN VUE HYBRID 2.4 4 Auto(L4) F 34.0 3474

CHEVROLET HHR PANEL FWD 2.4 4 Auto(L4) F 30.5 11.4 3208

SATURN VUE** 2.2 4 Auto(L4) F 29.8 14.1 3207

Honda IMA-Type Hybrid Comparison 

HONDA CIVIC HYBRID* 1.3 4 Auto(AV) F 58.8 2875

HYUNDAI ACCENT 1.6 4 Auto(L4) F 36.7 60.2 2403

 

HONDA ACCORD HYBRID 3 6 Auto(L5) F 36.3 3605

HONDA ACCORD 3 6 Auto(L5) F 27.4 32.5 3344

 

2-Motor Hybrid Comparison

NISSAN ALTIMA HYBRID 2.5 4 Auto(AV) F 46.7 3482

NISSAN ALTIMA 2.5 4 Auto(AV) F 34.3 36.1 3184

TOYOTA CAMRY HYBRID 2.4 4 Auto(AV) F 45.9 3680

TOYOTA CAMRY 2.4 4 Auto(L5) F 31.9 43.8 3307

TOYOTA PRIUS* 1.5 4 Auto(AV) F 65.8 2932

NISSAN VERSA 1.8 4 Auto(AV) F 37.7 74.6 2749

FORD ESCAPE HYBRID FWD 2.3 4 Auto(AV) F 40.6 3627

FORD ESCAPE FWD 2.3 4 Auto(L4) F 28.1 44.7 3256

LEXUS RX 400H 2WD 3.3 6 Auto(AV) F 35.0 4190

HYUNDAI SANTAFE 2WD 3.3 6 Auto(L5) F 25.5 37.1 4022

TOYOTA HIGHLANDER HYBRID 2WD 3.3 6 Auto(AV) F 35.0 4070

TOYOTA HIGHLANDER 2WD 3.3 6 Auto(L5) F 25.0 39.9 3649

FORD ESCAPE HYBRID 4WD 2.3 4 Auto(AV) 4 36.5 3792

FORD ESCAPE 4WD 2.3 4 Auto(L4) 4 26.1 39.4 3407

LEXUS RX 400H 4WD 3.3 6 Auto(AV) 4 34.3 4365

HYUNDAI SANTAFE 4WD 3.3 6 Auto(L5) 4 24.8 38.0 4322

MERCURY MARINER HYBRID 4WD 2.3 4 Auto(AV) 4 36.5 3787

MERCURY MARINER 4WD 2.3 4 Auto(L4) 4 26.1 39.4 3409

TOYOTA 

HIGHLANDER HYBRID 

4WD 3.3 6 Auto(AV) 4 34.3 4275

TOYOTA HIGHLANDER 4WD 3.3 6 Auto(L5) 4 24.1 42.4 3880
           Energy and Environmental Analysis, Inc. 3‐17   

The MSRP comparison at constant displacement is meaningful only in cases where the 

same engines are used in hybrids vs. non hybrid models within the same model family. 

The MSRP price figures advertised by OEMs are substantially higher for hybrid models 

and vary from $2,525 (Escape 2WD) to $7,740 (Accord). It should be noted that in most 

cases the hybrid models are sold with other upgrades, so the MSRP comparison does 

not directly relate to hybrid costs, although EEA’s estimates do fall with this range. 

In addition to large fuel economy advantage, the full hybrid vehicles do offer large 

performance gain due to the electrical traction motor power assist availability. That is 

the reason why Toyota Prius and Honda Civic HEVs are able to achieve desirable 

performance despite highly downsized, about 30%, IC engines. 

Table 4-7 summarizes the MY 2007 hybrid vehicle data compared with corresponding 

conventional models, in most cases, equipped with larger engines. The total power 

rating was used as a proxy for the conventional model selection on “competitive power” 

basis. The mild hybrids are excluded from this analysis since their power assist feature 

provides only marginal performance advantage. 

The analysis shows that very large fuel economy gains are realized in most hybrid 

cases on a “competitive performance basis”, although the results are highly variable. If 

the hybrids are compared to leading fuel economy performance vehicles, such as 

Murano 3.5L CVT, the advantage is about 35%. Fully optimized HEV offerings, such as 

the Prius, can achieve as much as 75% fuel economy advantage, on a competitive 

performance basis. 
3‐18   Energy and Environmental Analysis

Table 3-7. MY 2007 Hybrid Vehicle Fuel Economy, Key Specifications and MSRP 

Comparison on “Competitive Performance Basis”. 

FE – Fuel Economy – is EPA Combined Unadjusted; 

*-With MY 2007, Toyota upgraded the Camry V6 to 3.5L. The previous, MY2006 3.3L V6, model provides 

better power rating match. 

**-Ford markets the Escape and Mariner HEVs with de-rated power IC engine but claims the “V6-like” 

acceleration performance. 

***The Altima V6 is rated 270hp so Saturn Aura is used to provide better performance match. 

MFR CAR LINE DISP CYL TRANS DRIVE 

Fuel 

Economy 

[mpg] 

FE 

Diff. 

[%] FUEL 

Total 

Power 

[hp] 

Curb 

Weight

[lbs] 

Honda IMA-Type Hybrid Comparison

HONDA CIVIC HYBRID 1.3 4 Auto(AV) F 58.8 R 110 2875

HONDA CIVIC 1.8 4 Auto(L5) F 39.0 50.9 R 140 2690

 

HONDA ACCORD HYBRID 3 6 Auto(L5) F 36.3 R 253 3605

HONDA ACCORD 3 6 Auto(L5) F 27.4 32.5 R 244 3344

 

2-Motor Hybrid Comparison 

NISSAN ALTIMA HYBRID 2.5 4 Auto(AV) F 46.7 R 198 3482

SATURN AURA*** 3.5 6 Auto(L4) F 28.5 64.1 R 224 3578

 

TOYOTA CAMRY HYBRID 2.4 4 Auto(AV) F 45.9 R 192 3680

TOYOTA CAMRY (MY 2006)* 3.3 6 Auto(S5) F 27.8 65.3 R 190 3340

 

TOYOTA PRIUS 1.5 4 Auto(AV) F 65.8 R 110 2932

NISSAN VERSA 1.8 4 Auto(AV) F 37.7 74.6 R 122 2749

 

FORD ESCAPE HYBRID FWD** 2.3 4 Auto(AV) F 40.6 R 155 3627

FORD ESCAPE FWD 3 6 Auto(L4) F 25.4 59.7 R 200 3300

LEXUS RX 400H 2WD 3.3 6 Auto(AV) F 35.0 P 268 4190

LEXUS RX 350 2WD 3.5 6 Auto(L5) F 25.7 36.0 P 270 3870

TOYOTA HIGHLANDER HYBRID 2WD 3.3 6 Auto(AV) F 35.0 R 268 4070

NISSAN MURANO 3.5 6 Auto(AV) F 25.9 35.3 P 240 3983

FORD ESCAPE HYBRID 4WD** 2.3 4 Auto(AV) 4 36.5 R 155 3792

FORD ESCAPE 4WD 3 6 Auto(L4) 4 24.1 51.5 R 200 3492

LEXUS RX 400H 4WD 3.3 6 Auto(AV) 4 34.3 P 268 4365

LEXUS RX 350 4WD 3.5 6 Auto(S5) 4 24.6 39.3 P 270 4090

MERCURY MARINER HYBRID 4WD** 2.3 4 Auto(AV) 4 36.5 R 155 3787

MERCURY MARINER 4WD 3 6 Auto(L4) 4 24.1 51.5 R 200 3464

TOYOTA HIGHLANDER HYBRID 4WD 3.3 6 Auto(AV) 4 34.3 R 268 4275

NISSAN MURANO AWD 3.5 6 Auto(AV) 4 25.2 36.0 P 240 3983

The MSRP figures, on performance basis, can be used to gage the current pricing 

strategies for hybrids and do appear to provide useful reference points. In some cases, 

for example the Altima HEV versus Altima V6, the MSRP difference is relatively low 
           Energy and Environmental Analysis, Inc. 3‐19   

($990). In other cases, such Escape HEV versus Escape V6 ($3,805) the difference 

approaches EEA estimates. 

The EEA fuel economy estimates in Table 4-5 for the full 2-motor and IMA-type hybrids 

do agree with the FTP near term data on a competitive performance basis for models 

that are optimized for fuel economy performance (such as Prius, Civic, Altima and 

Escape/Mariner). However, the mild hybrids in 2007 do appear to report much higher 

fuel economy advantage relative to the EEA figures largely because they incorporate 

other technological improvements. The Vue fuel economy performance is tricky to 

compare because the regular I4 model uses a smaller 2.2L engine, while the hybrid Vue 

is over 200lbs heavier. If these differences are accounted for, the fuel economy 

difference would increase significantly. Similarly, the Aura BAS comparison to regular 

Aura is not meaningful since the regular model is only available with V6 engines in 

2007. If the Aura BAS is compared to 3.5L Aura, the fuel economy difference is 25%. 

Technology development examples and new model announcements described in 

previous sections illustrate that hybrids will likely achieve even larger fuel economy 

improvements compared to systems represented by MY 2007 data. Also large cost 

reductions can be anticipated with next generation HEVs as new optimized systems and 

suppliers enter the market with mass volumes. 
3‐20   Energy and Environmental Analysis

3.3 References for Section 4 

                                                                  1

 L. Wehrly, EPA, “Light-Duty Diesels in the US”, Presentation to the 2007 SAE 

Government Industry Meeting, May 16, 2007. 

2

 G. Schmidt, Ford “Light Duty Diesels in North America, a Huge Opportunity”, 

Presentation at DEER Conference, 2006. 

3

 F. Steinparzer, W. Mattes, et al., “The New BMW 2.0L 4-Cylinder Diesel Engine”, 

Vienna Motor Symposium, April 2007. 

4

 T. Abe, “Clean Technology for Global Diesel Expansion”, Presentation to the 2007 

SAE Government Industry Meeting, May 16, 2007. 

5

 T. Cartus, M. Schussler, et al., “SCR and DPF – from the Concept to Series 

Production. Mastering Complex, Multi-Dimensional Challenges”, Vienna Motor 

Symposium, April 2007. 

6

 J. German, “Honda Statement before the Senate Committee on Energy and Natural 

Resources”, US Senate, January 30, 2007. 

7

 Y. Sakai, H. Ishiyama, “Power Control Unit for High Power Hybrid System”, SAE 

Technical Paper 2007-01-0271. 

8

 G. Smyth, A. Lippert, “The Drive for Energy Diversity and Sustainability: the Impact on 

Transportation Fuels and Propulsion System Portfolios”, Vienna Motor Symposium, 

April 2007. 

9

 P. Savagian, “The GM 2Mode Hybrid System and 2008 Hybrid Chevrolet Tahoe and 

GMC Yukon”, Presentation to the 2007 SAE Government Industry Meeting, May 16, 

2007. 

10 Y. Dubel, “Valeo StARS Roadmap”, Presentation Provided to EEA, June 19, 2007. 

11 Dr. Klaus Egger, “Electronics and Mechantronics Increase Fuel Economy”, Aachen 

Colloquium, Automobile and Engine Technology, October 2006.