1

Memo 

To: Docket EPA-HQ-OAR-2009-0472 

From: Joseph McDonald, U.S. EPA-OTAQ-ASD 

CC: Ed Nam, U.S. EPA-OTAQ-ASD 

Date: Tuesday, March 24, 2010 

Re: Mercedes BlueEfficiency Vehicles

The attached Mercedes press release describes Mercedes BlueEfficiency package that reduced the 

fuel consumption of their C-class vehicle by 12%. 
Accessed on the Internet on March 24, 2010 at the following URL: 

http://media.daimler.com/dcmedia/0-921-1050602-1-1050604-1-0-0-0-0-1-11701-854934-0-1-0-

0-0-0-0.html

Improved aerodynamics, lightweight construction, tyres and drive 

technology - BlueEFFICIENCY in the C-Class: Fuel consumption 

reduced by 12 per cent 

Stuttgart, Feb 28, 2008 

From spring 2008, Mercedes-Benz will be adding three extra-economical 

BlueEFFICIENCY saloons to the C-Class range. A raft of intelligent measures and 

technologies has enabled the fuel consumption of the high-volume C 180 KOMPRESSOR 

and C 200 CDI models to be reduced by up to twelve per cent, while retaining the high 

levels of comfort and safety typical of a Mercedes. The BlueEFFICIENCY version of the 

100 kW/136 hp C 200 CDI consumes only 5.1 litres per 100 kilometres, while the C 180 

KOMPRESSOR BlueEFFICIENCY with 115 kW/156 hp covers 100 kilometres with 6.5 

litres of premium petrol. This corresponds to 135 and 156 grams of carbon dioxide, 

respectively, per kilometre. The third BlueEFFICIENCY C-Class model on show in 

Geneva is the C 350 CGI with direct petrol injection. The six-cylinder unit burns around 

ten per cent less fuel than the saloon with the current V6 engine.

For the new BlueEFFICIENCY models, Mercedes engineers have harnessed potentials from all 

fields of development to reduce weight, aerodynamic drag and rolling resistance yet further, and 

to organise the onboard energy management of these saloons even more efficiently. Together, 

these measures add up to a fuel saving on the NEDC driving cycle of 0.9 litres per 100 

kilometres for the C 180 KOMPRESSOR, and 0.6 litres for the C 200 CDI. 

The specialists in Sindelfingen have made very detailed improvements to the comprehensive 

lightweight construction concept of the C-Class, and have managed to shave off between 19 and 

32 kilograms of weight depending on the model. This achievement is in part due to a newly 

developed windscreen made of laminated glass, which weighs around 1.2 kilograms less than 

before. This is made possible by a technology transfer from the Maybach luxury saloon: between 

the panes of glass lies a new, acoustically effective plastic membrane which efficiently absorbs 

wind noise. This has enabled Mercedes engineers to reduce the thickness of the windscreen, 

achieving a further weight reduction without compromising noise comfort in any way. 

The noise-insulating lining of the firewall has also been weight-optimised with the help of 

special materials and the latest calculation methods. Using computer simulations, MercedesBenz recalculated the required firewall insulation and precisely redefined the material thickness 

of the sound-absorbing resinous foam in line with the noise input. This needs-driven redesign 

reduces the weight of the lining by around 20 per cent. 

Forged lightweight wheels also have a positive effect on the weight. These tip the scales at 

around 1.8 kilograms less than conventional light-alloy wheels, saving a total of more than seven 

kilograms per vehicle. These new lightweight wheels (6 J x 16 ET 39), which have aerodynamic 

benefits too, are standard equipment for the new BlueEFFICIENCY variants of the C 180 

KOMPRESSOR and C 200 CDI. 

Newly developed tyres: 17 per cent less rolling resistance

In addition to lightweight construction measures, Mercedes-Benz also devoted particular 

attention to reducing rolling resistance and aerodynamic drag. In collaboration with Michelin, 
Accessed on the Internet on March 24, 2010 at the following URL: 

http://media.daimler.com/dcmedia/0-921-1050602-1-1050604-1-0-0-0-0-1-11701-854934-0-1-0-

0-0-0-0.html

Mercedes engineers developed lightweight tyres with a particularly low rolling resistance. These 

are now receiving their series production premiere in the C-Class, and help to reduce fuel 

consumption. 

Rolling resistance is primarily caused by tyre deformation as the tyre contacts 

the road surface. This has a braking effect on the car, since additional energy is required to 

overcome this deformation resistance - therefore, the higher the rolling resistance, the higher the 

fuel consumption. Up to around 100 km/h, rolling resistance has a greater effect on fuel 

consumption than aerodynamic drag. 

The belt of this newly developed tyre for the C-Class contains a multi-layered mesh of highstrength steel for less deformation. It is also lighter in weight than conventional designs, enabling 

a further 1.7 kilograms or so to be saved per set of tyres. The secret, however, mainly lies in the 

chemical composition: the rubber compound for the treads and side walls is designed to ensure 

that rolling resistance is reduced by 17 per cent, while retaining the same good handling and 

braking characteristics. 

Aerodynamic fine-tuning: Cd figure an outstanding 0.25

At 120 km/h, the aerodynamic drag of the vehicle body already accounts for around 50 per cent 

of all the dynamic resistance a passenger car must overcome. Accordingly Mercedes-Benz has 

been very active in the field of aerodynamics for many years, and has achieved remarkable 

advances that have had a positive impact on the fuel consumption figures of cars bearing the 

Mercedes star. 

With a drag coefficient (Cd figure) of 0.27, the C-Class is among the most aerodynamically 

efficient notchback saloons in its market segment. This is the result of a whole series of 

intelligent details, such as the tail lights with ventilation slits: these reduce drag by influencing 

the airflow along the side walls, causing it to break off at the tail lights without causing 

turbulences behind the vehicle's rear end. In this way the patented tail lights of the C-Class 

replace the usual spoiler lips. 

In the new BlueEFFICIENCY versions of the C 180 KOMPRESSOR and C 200 CDI, Mercedes 

engineers have succeeded in bettering even the highly impressive Cd figure of the C-Class with a 

number of other detailed measures: 

• Smooth underbody cladding ensures that the air can flow beneath the vehicle body 

without turbulences. The full engine compartment and underbody panelling of the diesel 

models is also standard equipment in the BlueEFFICIENCY version of the C 180 

KOMPRESSOR. 

• Partially blanking off the radiator grille reduces the airflow into the engine compartment, 

thereby lowering wind resistance. Adequate cooling of the four-cylinder engines is of 

course uncompromised by this measure. 

• Sealing the joins between the bonnet and headlamps, as well as between the bumper and 

headlamps, improves the airflow around the front end. 

• The housings of the exterior mirrors were developed in the wind tunnel, and are 

particularly streamlined in form. 

• Lowering the suspension by 15 millimetres reduces aerodynamic drag, and has a 

particularly noticeable effect at higher speeds. 
Accessed on the Internet on March 24, 2010 at the following URL: 

http://media.daimler.com/dcmedia/0-921-1050602-1-1050604-1-0-0-0-0-1-11701-854934-0-1-0-

0-0-0-0.html

• The design of the new lightweight wheels also meets aerodynamic requirements, and 

improves the airflow around the vehicle flanks. 

Thanks to this package of aerodynamic measures the Cd figure for the new BlueEFFICIENCY 

models has been reduced by seven per cent to 0.25, representing another major contribution to 

fuel economy. 

Efficient energy management: needs-driven power steering control

It is not only intelligent lightweight construction, tyres with a low rolling resistance and good 

aerodynamics that help to further improve the economy and environmental compatibility of 

today's passenger cars. Intelligent control of ancillary units and the reduction of friction losses 

can also make an important contribution in this respect. 

Energy management is the key: in the BlueEFFICIENCY models of the C-Class, the power 

steering system is controlled on a needs-driven and therefore energy-saving basis. The standard 

power steering in the C-Class has an additional valve which switches off the servo pump when it 

is not required. While this pump operates continuously in all driving situations in conventional 

steering systems, the new valve interrupts the flow of hydraulic fluid when the car has followed a 

straight course for a while, switching off the servo pump. This has the advantage that the engine 

no longer needs to provide energy to drive the servo pump, meaning that it operates more 

economically. Thanks to this technology, the NEDC fuel consumption is cut by 0.14 litres per 

100 kilometres - which equates to a reduction of 2.5 per cent in the case of the C 200 CDI. 

As a further contribution to reduced weight and friction, the BlueEFFICIENCY C 180 

KOMPRESSOR and C 200 CDI saloons are equipped with a newly developed final drive 

featuring further-improved antifriction bearings, forged differential gears and a sophisticated 

lightweight construction. These measures reduce the friction forces within the transmission, 

hence the engine expends less energy in overcoming them. 

The longer final-drive ratios of the BlueEFFICIENCY versions also help to reduce fuel 

consumption. These are as follows: 

• C 180 

KOMPRESSOR: 

2.87 : 1 (rather than 

3.07 : 1) 

• C 200 CDI: 2.47 : 1 (rather than 

2.65 : 1) 

 

The C 180 KOMPRESSOR and C 200 CDI models are both equipped with the six-speed manual 

transmission with overdrive characteristics as standard. With a ratio of 0.838 : 1 and 0.828 : 1, 

respectively, sixth gear considerably lowers the engine speed and fulfils a major precondition for 

fuel-efficient driving. 

Useful information: new gearshift and fuel consumption display in the cockpit

A newly developed gearshift display in the cockpit informs the driver when he should change 

gear to save fuel. Experience gained during the Mercedes-Benz "ECO Training" courses has 

shown that drivers are able to make average fuel savings of up to 15 per cent with an economical 

and energy-conscious style of driving - without any loss of driving enjoyment. 
Accessed on the Internet on March 24, 2010 at the following URL: 

http://media.daimler.com/dcmedia/0-921-1050602-1-1050604-1-0-0-0-0-1-11701-854934-0-1-0-

0-0-0-0.html

In fact "ECO Training" will practically come as standard in the future BlueEFFICIENCY 

versions of the C-Class: in addition to gearshift recommendations, the instrument cluster features 

a newly developed display showing the present fuel consumption. This will appear in the centre 

of the speedometer as an easily legible bar chart. A brief glance at the display is sufficient to tell 

the driver the current fuel consumption in litres per 100 kilometres. The bar chart responds 

immediately when the driver changes to a higher gear or takes his foot off the accelerator to use 

the deceleration fuel cut-off function. 

Up-to-date engines: downsized C 180 with the same output

Under the bonnets of the new model variants can be found well-proven four-cylinder engines, 

which are amongst the bestselling power units in the model range: around one quarter of all CClass buyers opt for these four-cylinder engines. 

For the C 180 KOMPRESSOR Mercedes-Benz has reduced the overall displacement from 1796 

to 1597 cubic centimetres, while retaining the same output (115 kW/156 hp) and torque (230 

Newton metres). This downsizing of the engine's displacement, combined with measures for 

optimising the combustion chamber, mixture formation and engine friction, adds up to a total 

potential fuel saving of 0.35 litres per 100 kilometres. 

All in all, the NEDC fuel consumption of the C 180 KOMPRESSOR in BlueEFFICIENCY guise 

is just 6.5 litres of premium petrol per 100 kilometres. This is 0.9 litres or twelve per cent less 

than for the standard production model. 

The displacement, output and torque of the CDI engine remain unchanged. The package of 

efficiency measures has enabled the NEDC fuel consumption of the BlueEFFICIENCY version 

of the C 200 CDI to be cut by 0.6 litres (10.5 per cent) to just 5.1 litres per 100 kilometres. This 

corresponds to CO2 emissions of 135 grams per kilometre. 

Key engine, performance and fuel consumption figures at a glance: 

 C 180 KOMPRESSOR 

BlueEFFICIENCY 

C 200 CDI 

BlueEFFICIENCY

Displacement 1597 cc 2148 cc 

Output 115 kW/156 hp at 5200 

rpm 

100 kW/136 hp at 3800 

rpm 

Max. torque 230 Nm at 3000-4500 

rpm 

270 Nm at 1600-3000 

rpm 

0-100 km/h 9.5 s 10.4 s 

Top speed 230 km/h 220 km/h 

NEDC 

consumption*

6.5 l/100 km 5.1 l/100 km 

CO2 emissions 156 g/km 135 g/km 

*combined consumption 

C 350 CGI: ten per cent more economical thanks to direct petrol injection

As of late 2008, the BlueEFFICIENCY C-Class line-up will be rounded off by the world's first 

petrol engine with spray-guided direct injection. Cue the new C 350 CGI BlueEFFICIENCY, 
Accessed on the Internet on March 24, 2010 at the following URL: 

http://media.daimler.com/dcmedia/0-921-1050602-1-1050604-1-0-0-0-0-1-11701-854934-0-1-0-

0-0-0-0.html

which is being presented by Mercedes-Benz at the Geneva Motor Show. Despite generating a 

higher power output and even greater torque, the new model consumes around ten per cent less 

fuel than the C 350 saloon with the current V6 engine. The C 350 CGI is therefore set to offer a 

hitherto unrivalled combination of power delivery, agility, safety, economy and environmental 

compatibility in this vehicle class. 

The CGI engine summons up an output of 215 kW/292 hp and 365 Newtonmetres of peak torque 

at 3000 rpm. 15 kW/20 hp and 15 Newtonmetres more respectively than the current V6 unit with 

port injection. Thanks to state-of-the-art engine technology, fuel consumption of the C 350 CGI 

BlueEFFICIENCY has been cut to approx. 8.4 litres per 100 kilometres (provisional NEDC 

figure), approx. one litre below the figure for the current C 350. As such, the new six-cylinder 

engine makes a major contribution to reducing carbon dioxide emissions. These significantly 

improved output and fuel consumption figures are achieved whilst still using cost-efficient 

premium grade petrol (RON 95). 

The CGI unit also offers an impressive driving experience combined with superb economy and 

environmental compatibility: the C 350 CGI BlueEFFICIENCY takes just 6.2 seconds to 

accelerate from 0 to 100 km/h and is capable of an electronically limited top speed of 250 km/h 

(provisional figures).Mercedes-Benz became the first car maker to put spray-guided direct petrol 

injection into series production in 2006. This technology is markedly superior to the direct 

injection system with wall-guided combustion used by other car makers, as the Mercedes 

technology achieves far better fuel utilisation due to its higher thermodynamic efficiency, 

meaning both reduced fuel consumption and lower exhaust emissions. 

The six-cylinder engine demonstrates its particular strengths during stratified-charge operation 

when the powerplant operates with a high excess of air and is thus very fuel-efficient. In the 

Mercedes direct injection engine, this favourable lean-burn operation with a stratified charge in 

the combustion chamber is also possible for the first time at higher engine speeds and load 

ranges because the engine's combustion chambers are injected with several successive jets of fuel 

in fractions of a second during each power stroke, thereby substantially improving mixture 

formation, combustion and consumption. Whereas stratified-charge operation was previously 

only feasible over a limited partial load range, the CGI six-cylinder engine can now be operated 

in stratified charging mode over a wider range. 

Piezoelectric injectors: enabling lightning fast multiple injection

High-speed, ultra-precise piezoelectric injectors are among the key components of the secondgeneration direct petrol injection system. The invention of these injectors has spawned virtually 

all the advances in the spray-guided combustion system. The piezoelectric valves open their 

injectors outwards to create an annular gap just a few microns wide, allowing the fuel jet to form 

with a uniform, hollow cone-shaped pattern. Thanks to millisecond switching times, the 

piezoelectric injectors also permit the multiple injection that promotes lean-burn operation and 

helps create the ideal conditions for the engine's exemplary consumption figures. A highpressure pump with downstream distributor and pressure valve supplies the fuel and regulates the 

amount delivered in accordance with requirements. With a pressure of up to 200 bar, the system 

develops around 50 times the fuel pressure of a conventional port-injection system. 

The combustion system developed by the Mercedes engineers, with multiple, closely spaced 

injections during each power stroke, also serves to enhance the V6 engine's smooth running and 
Accessed on the Internet on March 24, 2010 at the following URL: 

http://media.daimler.com/dcmedia/0-921-1050602-1-1050604-1-0-0-0-0-1-11701-854934-0-1-0-

0-0-0-0.html

emissions characteristics. Measurements show that untreated emissions (hydrocarbons) are 

reduced by more than half in the warm-up phase. Active control of injection and combustion also 

produces higher temperatures in the exhaust manifold, thereby warming up the catalytic 

converters faster. 

The data for the new C 350 CGI BlueEFFICIENCY at a glance: 

Displacement 3498 cc 

Bore/stroke 92.9/86.0 mm 

Compression ratio 12.2 

Output 215 kW/292 hp at 6400 rpm 

Max. torque 365 Nm at 3000-5100 rpm 

NEDC fuel 

consumption

8.4 l/100 km* 

Acceleration 0-100 

km/h

6.2* 

Top speed 250 km/h** 

*provisional figures; **electronically limited 

 

Four-valve technology, variable camshaft adjustment for the intake and exhaust sides, two-stage 

intake manifold, balancer shaft and an intelligent heat management system with map-controlled 

thermostat are some of the other technical highlights that the direct injection engine has adopted 

from the port-injected C 350 engine. The crankcase and cylinder head are made out of 

aluminium; the cylinders are fitted with low-friction, dimensionally stable liners made out of a 

lightweight aluminium-silicon alloy. 

BlueEFFICIENCY: additional fuel-saving measures

The package of BlueEFFICIENCY measures for the direct-injection petrol unit incorporates 

further fuel-saving technologies besides. These include the newly developed windscreen made of 

laminated glass, which weighs around 1.2 kilograms less than before, forged lightweight wheels 

and low rolling resistance tyres. 

The needs-driven and therefore energy-saving control of the power steering also forms part of 

the standard specification on the C 350 CGI. Finally, Mercedes-Benz has further improved the 

saloon's very low aerodynamic drag by fitting new, streamlined exterior mirror housings. A 

variable radiator shutter improves the airflow around the front end and, depending on the driving 

situation, also allows control of the air supply to the six-cylinder engine in line with 

requirements.