P.1 

OAR Box 1830 

Prepped by Ollie Stewart 

Document Number: 

23) IV-B-19 

Docket Number: 

A-87-11 

Printed 11/13/2008 7:20:52 AM Sheet 23 of 232 
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 UN,TE ° ^ ^ E ^^ONMENTAU PROTECT,ON A GENC Y *"*'! % 

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 AN N ARBOR. MICHIGAN 48105 ' 7 

DEC 2 2 1988 

MEMORANDUM 

SUBJECT: 

j 

AUG - 1 1991 

EPA AIR Dl 

OFFICE OF 

AIR AND RADIATION 

Onboard and Evaporative Control Svstem Co 

^i?^?L f 0 r the Supplemental Notice 'of "rooos Rulemaking 

st 

ed 

FROM: 

TO: 

THRU: 

Jean Schwendeman, Mechanical Engineer 

Standards Development and Support Bran 

vvl.^W^ >—-W*-t.*U*j*v 

The Record 

Glenn w. Passavant, Senior Project Manager v'-^i^fiu_~4" 

standards Development and Support Branch 

i

i

 = n" d /-n Ryk ?

WSki ' Senio r Project Manager'/^--ff?, 

Stanoards Development and Support Branch ^ /fi£^' 

Introduction 

for

 Ttl

a

is. memorandum describes in detail the new cost estimates 

or ,Zr°, V evaporative system and the onboard refusing 

vapor recovery system, as discussed in the Supplemental Notice 

of Proposed Rulemaking. The analysis for the 'moroved 

evaporative system was performed for both 9.0 and U . 5 ~o 

certification fuel. As is discussed further below, the onboard 

analysis assumes a 9.0 psi RVP certification fuel ° n °

o a ^ 
P.3 

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"excess" evaporative system - the vehicle-based system 

designed for control of evaporative emissions as outlined 

in the proposed volatility/evaporative rulemaking (52 FR 

31274). The estimated cost for this system was calculated 

as an incremental cost to the current evaporative system. 

The detailed cost analysis of this system is found in the 

July, 1987 Volatility, Draft Regulatory Impact Analysis.[l] 

"improved" evaporative system - the vehicle-based system 

designed for control of evaporative emissions as outlined 

in the supplemental notice of proposed rulemaking. This 

system would be designed to control "running losses" and 

other evaporative emissions not controlled by either the 

current or excess evaporative systems. The estimated cost 

for this system was calculated incremental to the cost of 

tjhe excess evaporative system. 

"^original" onboard system - the vehicle-based system 

designed to control refueling emissions using hardware 

similar to that described in the onboard proposal (52 FR 

31162). The estimated cost for this system was calculated 

incremental to the cost of the excess evaporative system. 

The detailed cost analysis of this system is found in the 

July, 1987 "Evaluation of Air Pollution Regulatory 

Strategies for Gasoline Marketing Industry - Response to 

Public Comments".[2] 

"revised" onboard system - the vehicle-based system 

designed to control refueling emissions using hardware 

Similar to that described in the supplemental notice of 

proposed rulemaking. The estimated cost for this system 

was calculated as an incremental cost to improved 

evaporative systems and totally replaces the original cost 

estimate for the onboard system. 

The original onboard and the excess evaporative emission 

regulations (commonly referred to as the Volatility proposal) 

were both published in the Federal Register on August 19, 

1987. The onboard proposal was developed to mandate recovery 

of emissions from vehicle fuel tanks during refueling. The 

excess evaporative proposal was developed to match in-use and 

certification gasoline RVPs and to control evaporative 

emissions related to insufficient canister purge in-use. This 

would be done by requiring the test vehicle to start the 

driving cycle (FTP) with a saturated evaporative canister. 

At the time of the original proposals, EPA fully expected 

that manufacturers would use integrated rather than separate 

refueling and evaporative control systems. Integrated systems 

would provide a degree of control of running losses and other 

evaporative emissions which sometimes occur during in-use 

operation, because the portion of the canister necessary to 

handle a load of refueling vapors is available to handle these 

other! types of emissions during much of the time between 
^ 4 ^ 

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refueljings. However, many manufacturers have indicated to EPA 

that under the original test procedures they would use separate 

systems which may not provide the extra degree of control of 

evaporjative and running loss emissions which would be provided 

by an integrated system. Since the original proposals, EPA has 

learned that these emissions contribute a much larger 

percentage to the VOC inventory than was previously thought. 

The magnitude of the problem makes it clear that these 

emissions would need to be controlled regardless of whether 

onboarjd refueling controls are required. 

i 

Because of these developments, the supplemental proposals 

include revisions to both the onboard and evaporative proposals 

to ensure that running losses and other evaporative emissions 

previously uncontrolled under the Federal Test Procedure would 

be controlled by either integrated or separate control systems 

if onboard refueling controls are required. Furthermore, these 

running loss and other evaporative emissions would have to be 

controlled by the vehicle with an improved evaporative system 

under ' the newly proposed evaporative regulations even if 

onboarjd refueling controls are not mandated. 

The revised cost estimates detailed in this memo 

incorporate the effects of the changes to the onboard and 

evaporative proposals which are described above. The revised 

cost estimates are also based upon a simplified onboard system 

concept developed over the past year along with simplifications 

in thje refueling test procedure. These simplifications are 

described in the Supplemental Notice of Proposed Rulemaking. 

Because improved evaporative systems could potentially be 

requited independent of onboard refueling control, the costs of 

onboard controls are calculated as incremental to the costs of 

improved evaporative controls. The costs of both of these 

systems are calculated incrementally to the excess evaporative 

contrdl system described in the proposed volatility/evaporative 

rulemaking (52 FR 31274). Since this analysis is part of a 

reproposal, the methodology and values used in the original 

proposal were changed only where the above developments made it 

necessary. 

Summary of Estimated Costs 

The cost estimates were made for typical vehicles from all 

threej gasoline vehicle classes: light-duty vehicles (LDVs), 

lighttduty trucks (LDTs), and heavy-duty gasoline vehicles 

(HDGVs). The same 1989 projected sales were used as in the 

original onboard proposal: 11.2 million for LDVs, 3.71 million 

for LDTs and 0.384 million for HDGVs. These result in a sales 

weighting of 73.2 percent for LDVs, 24.3 percent for LDTs and 

2.5 percent for HDGVs. A summary of the estimated costs for 

the excess evaporative systems, improved evaporative systems, 
P.5 

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and the revised onboard systems for 9.0 RVP fuel is shown in 

Tables 1A, IB, and 1C, respectively. In addition, since these 

are incremental costs for each additional level of control (as 

defined above), a summation is shown in Table ID to indicate 

the total increase in vehicle cost due to the onboard refueling 

and evaporative control proposals. All values are in retail 

price equivalents (RPE) which is the price seen by the 

consumer. All values are also in 1988 dollars. Negative 

values indicate savings to the consumer. 
P.6 

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Table 1A 

Excess Evaporative System Costs 

(Incremental to Current Evap)* 

9.0 psi RVP Certification Fuel 

Vehicle 

LDV 

LDT 

HDGV 

Vehicle 

Cost Increase 

1.45 

1.85 

3.35 

Weight 

Penalty 

0.00 

0.00 

0.00 

Fuel Net Cost 

Recovery Credit** to Owner 

N.A. 

N.A. 

N.A. 

Sales Weighted Net Cost 

1.45 

1.85 

3.35 

1.60 

Vehicle 

LDV 

LDT 

HDGV 

Table IB 

Improved Evaporative System Costs 

(Incremental to Excess Evap)* 

9.0 psi RVP Certification Fuel 

Vehicle 

Cost Increase 

9.65 

13.40 

11.25 

Weight 

Penalty 

0.50 

1.15 

0.60 

Fuel Net Cost 

Recovery Credit to Owner 

12.30 

20;'65 

38.75 

- 2 

- 6 

- 2 6 

15 

10 

90 

Sales Weighted Net Cost -3.70 

* * 

Costs are in RPE for 1988 dollars rounded to the nearest nickel. 

Sales Weights: LDV 73.2%; LDT 24.3%; HDGV 2.5%. 

The total fuel recovery credit of excess evaporative systems would 

be the result of any vehicle changes and also of matching 

certification and in-use fuel RVPs. It is difficult to determine 

the portion of the credit due solely to vehicle changes, so none are 

used here. 
P.7 

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Table 1C 

Revised Onboard Control System Costs 

(Incremental to Improved Evap)* 

9.0 psi RVP Certification Fuel 

Vehicle 

LDV 

LDT 

HDGV 

Vehicle 

Cost Increase 

0.90 

1.50 

5.20 

Weight 

Penalty 

0.00 

0.00 

0.00 

Fuel 

Recovery Credit 

4.20 

6.65 

12.60 

Net Cost 

to Owner 

-3.30 

-5.15 

-7.40 

Sales Weighted Net Cost -3.90 

Vehicle 

LDV 

LDT 

HDGV 

Table ID 

Total Costs for Onboard and 

Evaporative System Changes* 

9.0 psi RVP Certification Fuel 

Vehicle 

Cost Increase 

12.00 

16.75 

19.80 

Weight 

Penalty 

0.50 

1.15 

0.60 

Fuel 

Recovery Credit 

16.50 

27.30 

51.35 

Net Cost 

to Owner 

-4.00 

-9.40 

-30.95 

Sales Weighted Net Cost -6.00 

Costs are in RPE for 1988 dollars rounded to the nearest nickel 

Sales Weights: LDV 73.2%; LDT 24.3%; HDGV 2.5%. 
P.8 

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Four values are shown for each level of control and each 

vehicle class: vehicle cost increase, weight penalty, fuel 

recovery credit, and net cost to the consumer. The vehicle 

cost increase reflects the additional "sticker price" for a 

typical vehicle with the indicated additional level of emission 

control. The weight penalty reflects the slight increase in 

vehicle weight due to the additional emission controls and is 

quantified in terms of the cost of the additional fuel consumed 

by the vehicle over its lifetime due to this additional 

weight;. The fuel recovery credit is the savings in lifetime 

fuel costs due to the consumption of recovered fuel vapors by 

the erigine. The net cost to the owner is the summation of the 

vehicle cost increase and the weight penalty less the fuel 

recovery credit. The weighted net cost is the weighting of the 

net costs of LDVs, LDTs, and HDGVs by the fraction of total 

sales of the vehicle class. The same sales fractions are used 

here as those detailed in Volume II of the Refueling Controls 

Draft Regulatory Impact Analysis.[3] 

A summary of the estimated costs of excess evaporative 

systems and improved evaporative systems for 11.5 RVP fuel is 

shown in Tables 2A and 2B, respectively. A summation is shown 

in Table 2C. Once again, all values are RPEs in 1988 dollars. 

The weight penalties and fuel recovery credits were not 

calculated for the revised onboard systems using 11.5 RVP 

fuel. This is because only the vehicle costs of excess 

evaporative and improved evaporative systems were needed to 

determine the cost effectiveness of evaporative and volatility 

controls. That analysis showed that it appeared to be cost 

effective to limit in-use fuel to 9.0 RVP. Because of that 

result, the costs of onboard systems were calculated 

incrementally to improved evaporative systems only at 9.0 RVP. 

Discussion of Improved Evaporative Systems 

Existing evaporative systems are only designed to handle 

typical diurnal and hot soak emissions generated under average 

temperature conditions and at average frequencies of 

occurrence. The improved evaporative system would have the 

capacity to handle these types of evaporative emissions when 

they are generated under more extreme conditions such as the 

high temperatures typical of ozone violation days and the 

multiple diurnals which occur if a vehicle is not used for 

several consecutive days. The improved evaporative systems 

would also have the capacity to handle running losses which are 

caused by high road temperatures and hot fuel returned from the 

engine compartment which heats and sometimes even boils the 

fuel in the fuel tank. At present, in many fuel system 

designs, a large amount of these fuel tank vapors leak into the 

atmosphere. 
P.9 

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Table 2A 

Excess Evaporative System Costs 

(Incremental to Current Evap)* 

11.5 psi RVP Certification Fuel 

Vehicle 

Vehicle Cost Increase 

LDV 5.05 

LDT 6.25 

HDGV 9.35 

Table 2B 

Improved Evaporative System Costs 

(Incremental to Excess Evap)* 

11.5 psi RVP Certification Fuel 

Vehicle 

LDV 

LDT 

HDGV 

Table 2C 

Total Costs for Evaporative System Changes* 

11.5 psi RVP Certification Fuel 

Vehicle 

LDV 

LDT 

HDGV 

Vehi Lcle 

Cost Increase 

26 

37 

34 

75 

90 

80 

Vehicle 

Cost Increase 

31 

44 

44 

80 

15 

15 

Notes: 11.5 psi RVP certification fuel. Costs are in RPE 

for 1988 dollars rounded to the nearest nickel. 
P.10 

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Ibproved evaporative systems are able to capture these 

additional emissions if significantly larger canisters are used 

than those found on existing evaporative control systems. The 

size of the canister has a large effect on system cost, as well 

as ori system effectiveness. EPA has been analyzing the 

relationship between the canister size and the operational 

characteristics of the purge system and through this effort has 

developed a new canister sizing model. The new model makes use 

of instantaneous driving schedule speeds and accelerations in 

contrast to average values. With this procedure, interactions 

between driving patterns, purge control and flow rate, fuel 

tank vapor generation and charcoal adsorption characteristics 

are more realistically simulated. Changes in the canister load 

and the quantity of hydrocarbons purged from the canister are 

predicted as a function of time. The model is detailed in the 

PT Model Description and Users Guide.[4] 

EPA estimates that canisters on LDVs will increase from 

1.3 liters (L) for excess evaporative systems to 2.7 L with 9.0 

RVP certification fuel for improved evaporative systems. The 

1.3 L size of the excess evaporative canister is the average of 

current LDV evaporative canisters as was determined in a survey 

detailed in EPA's Volatility Draft Regulatory Impact 

Analysis, [ll The 2.7 L average size for LDV improved 

evaporative systems is based upon the new model. Similarly, if 

11.5 RVP certification fuel is used, canisters on LDVs may 

increase in size from 2.1 L to 9.3 L. In addition, fuel 

cooling strategies may be required to minimize boiling. The 

canister sizes for the various systems on LDTs and HDGVs were 

derived following the same analysis as the LDVs. 

EPA expects that most LDV and LDT manufacturers will 

install the improved evaporative canister in the rear of the 

vehicle. This area often has more space than that which is 

available in the engine compartment. Since nearly all LDVs and 

LDTs are fuel injected there is no need to place the canister 

in the engine compartment to capture carburetor bowl-vent 

vapors. HDGV manufacturers will probably continue to place 

their canisters in the existing locations on their vehicles 

because of the greater amount of packaging space available. 

The number and size (diameter and length) of vapor lines 

going to and from the canister can also affect where canisters 

are placed. Canisters located in the rear of the vehicle are 

closer to the fuel tank, which will minimize the size of the 

vapor line between the fuel tank and canister. With the 

dominance of fuel-injected vehicles, the vapor line between the 

canister and carburetor bowl(s) is no longer needed and 

therefore is no longer a consideration for canister placement. 

Canisters will still need a purge line, but this line would be 

approximately the same size and follow the same routing from 

the rear-mounted canister to the engine compartment as the 

existing vapor line between the fuel tank and the front-mounted 
P.11 

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canister. The feasibility of rear-mounted canisters is 

supported by General Motors which is already placing 

evaporative canisters in that location on their W-body car line. 

Manufacturers will have to improve the purge system in 

order to handle the increased canister vapor load. EPA expects 

that manufacturers will increase the purge rate and will 

control the purge with frequency modulated solenoid valves. 

EPA expected these valves to be used on all vehicles to control 

excess evaporative emissions if certification fuel went to 11.5 

RVP. However, due to the much greater quantity of vapors which 

will be handled by improved evaporative systems, EPA now 

expects that frequency modulated solenoid valves will be used 

on all vehicles regardless of whether the certification fuel is 

9.0 or 11.5 RVP. 

These changes in the evaporative system increase the 

vehicle costs to control evaporative emissions. However, these 

changes also result in a reduced incremental vehicle cost 

allocated to the onboard control of refueling emissions. 

Discussion of Revised Onboard Systems 

EPA's concept of the hardware required for an onboard 

system has changed between the time of the original proposal 

and the supplemental proposal. Based on additional analysis 

and System testing, EPA learned that the proposed onboard 

system could be simplified. This concept change resulted in a 

significant reduction in the estimated system cost. The major 

changes in the revised onboard control system "concept since the 

original proposal are listed below. 

1. Canisters will be located in the rear of the 

vehicles instead of in the engine compartments (for LDVs and 

LDTs only). This will allow a smaller diameter and shorter 

vapor line to be used than that for a front-mounted canister. 

This location is consistent with the improved evaporative 

system discussed above. 

The estimates of the refueling control canister sizes have 

changed since the original proposal because the new modelling 

techniques used to size the improved evaporative canisters were 

also applied to refueling canisters. Another change in the 

analysis since the original proposal is that EPA assumed 

virtually all vehicles will be fuel-injected by the time that 

these proposals are implemented. On fuel injected vehicles, 

vapors are only collected from the fuel tank rather than from 

both the fuel tank and the carburetor vent bowl. With the fuel 

tank as the sole source for vapors, it was assumed that all 

vehicles will use integrated systems (one canister for both 

refueling and evaporative emissions control) for cost, design 

and safety reasons. 
P.12 

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2. Vapors will be routed from the top of the fuel tank 

through a vent/rollover valve, rather than from the fillneck. 

This change greatly simplifies the proposed onboard system. 

The existing external vent line between the fuel tank and 

fillneck opening can then be eliminated. In addition, the 

fillneck mounted valve described in the original proposal is no 

longer! needed. However, the vent/rollover valve used for 

evaporative emissions would have to be modified to accommodate 

a 10 gpm fuel dispensing rate and would also have to 

incorporate a fill limiting function. 

3:. The existing fillneck will provide a liquid seal 

without the use of a J-tube (on LDVs, LDTs, and light HDGVs). 

EPA has done testing which supports this concept. The heavier 

HDGVs, especially those with saddle-tanks, will still need some 

hardware changes to provide a seal. 

4. Liquid/vapor separators will not be required with 

the advent of onboard systems. This remains to be a 

manufacturers design option, as is the case on current vehicles. 

5. Anti-spitback valves will be used to improve 

refueling safety. Some manufacturers are already starting to 

install these devices in their product lines. 

As previously stated, these changes in approach and system 

concept resulted in a reduction in the estimated cost for 

onboard systems. A detailed discussion of the revised cost 

estimate for both onboard and improved evaporative systems now 

follows. 

Detailed Discussion of the Cost Analyses 

The cost analyses have been updated in the areas which 

were affected by the changes made in the proposed evaporative 

control regulation, changes in the onboard control system 

concept, and in the canister sizing model. Values not affected 

by these changes were adjusted for inflation, but are otherwise 

identical to the values used in the original proposals. The 

mark-up factor representing manufacturer and dealer profit is 

still 1.26 for LDVs and LDTs, and 1.27 for HDGVs. 

The adjustment for inflation was based on the ratio of 

Consumer Price Indexes (CPI) for new cars as recorded in MVMA 

Motor Vehicle Facts & Figures '86. At the time of the 

analysis, CPIs were only available through 1986. Using the 

1986 index of 224.4 and the 1984 index of 208.5, the inflation 

for a new car between 1984 and 1986 was found to be 7.6 percent 

(224.4 divided by 208.5). This same rate was also used to 

estimate the inflation between 1986 and 1988. The total 

inflation between 1984 and 1988 is therefore 15.8 percent. 
P.13 

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The improved evaporative and onboard system cost analysis 

is discussed in detail according to the following three 

categories: hardware costs, development costs, and recovery 

credits. Within each of these categories, a separate 

discussion will be made for the improved evaporative costs 

incremental to the excess evaporative costs and the revised 

onboard costs incremental to the improved evaporative costs. 

The colsts described below are for all gasoline LDVs, LDTs, and 

HDGVs. Notes are made where the values only refer to a subset 

of this group. 

A. Hardware Costs 

1. Introduction 

The hardware components discussed for the improved 

evaporative system are: canister, vapor lines, purge valve, 

vent/rbllover valve, and fuel cooling. No additional cost was 

allocated for ECU modifications. It was assumed that the net 

cost [allocated for reprogramming the ECU in the original 

volatility proposal (i.e., excess evaporative control) was 

sufficient for the total changes in the system. Table 3 

summarizes the costs for the improved evaporative systems 

incremental to excess evaporative systems for LDVs, LDTs 

(single and dual fuel tank), and HDGVs (single and dual fuel 

tank). Values are shown for both 9.0 and 11.5 psi RVP 

certification fuel. The costs are in RPE and have been rounded 

to the nearest nickel. 

The hardware components discussed for the revised onboard 

system are the: canister, vapor lines, vent/rollover valve, 

anti-spitback valve, and seal assembly (HDGVs). The revised 

onboard control system costs are shown in Table 4 and are 

incremental to those incurred for improved evaporative systems 

(Table 3). The canister costs are for canisters designed for 

9.0 psi RVP certification fuel. The costs are in retail price 

equivalents (RPE), which includes the markups for manufacturer 

and dealer profits. All values have been rounded to the 

nearest nickel. 

the original onboard and volatility proposals used two 

different approaches for analyzing the hardware required for 

HDGVs. The volatility proposal grouped all HDGVs together. 

The onboard analysis represented HDGVs as Class lib and Class 

VI vehicles, where Class lib vehicles represented 75 percent of 

the HDGV fleet and Class VI vehicles represented 25 percent of 

the fleet. The lib and VI vehicles were further distinguished 

as haying either single or dual fuel tanks. Eighty percent of 

the Class lib vehicles have single fuel tanks, while 20 percent 

have dual tanks. Eighty-five percent of the Class VI vehicles 

have single fuel tanks compared to 15 percent with dual tanks. 
Table 3 

Improved Evaporative System Hardware Cost (in RPE, 1988 $)* 

Item 

9.0RVP 

Canister $3.80 

Vapor Lines 0.20 

Purge Valve 1.05 

Vent/Rollover Valve 3.80 

Fuel Cooling System 0.00 

ECU Mods** 0.00 

LDV 

11.5RVP 

$15.65 

0.20 

0.00 

3.80 

6.30 

0.00 

LDT-S 

9.0RVP 11.5RVP 

$5.50 $21.60 

0.20 0.20 

1.05 0.00 

3.80 3.80 

0.00 6.30 

0.00 0.00 

Vehicle/Certification 

LDT-D 

9.0RVP 11.5RVP 

$11.00 $43.10 

0.40 0.40 

1.05 0.00 

7.55 7.55 

0.00 6.30 

0.00 0.00 

Fuel 

HDGV-S 

9.0RVP 11.5RVP 

$2.50 $17.35 

1.10 1.10 

1.05 0.00 

3.80 3.80 

0.00 6.35 

0.00 0.00 

HDGV-D 

9.0RVP 

$7.00 

2.15 

1.05 

7.60 

0.00 

0.00 

11.5RVP 

$39.40 

2.15 

0.00 

7.60 

6.35 

0.00 

Total $8.85 $25.95 $10.55 $31.90 $20.00 $57.35 $8.45 $28.60 $17.80 $55.50 

** 

Incremental to Excess Evaporative System. 

Cost previously allocated to Excess Evaporative System. 

I 
P.15 

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Table 4 

Onboard System Hardware Cost (in RPE, 1938$)* 

Component , 

Remove Ext'l Vent Line 

Vent/Rollover Valve 

Anti-Spitback Valve** 

Vapor Line 

Seal Assembly 

Carbon Canister*** 

LDV 

-1.60 

0.65 

0.35 

0.20 

0.00 

0.25 

LDT-S 

-1.60 

0.65 

0.35 

0.20 

0.00 

0.45 

LDT-D 

-3.20 

1.30 

0.70 

0.40 

0.00 

0.90 

Ilb-S 

-1.90 

0.65 

0.35 

1.20 

0.00 

0.90 

Ilb-D 

-3.80 

1.30 

0.70 

2.40 

0.00 

1.75 

VI-S 

0.00 

0.65 

0.35 

2.30 

4.20 

1.40 

VI-D 

0.00 

1.30 

0.70 

4.60 

8.40 

3.50 

Total -0.15 0.05 0.10 1.20 2.35 8.90 18.50 

* Incremental to Improved Evaporative System. 

** Some 'vehicles already have this hardware. Conservative 

estimate. 

*** Canisiter sized for 9.0 psi RVP 
P.16 

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The analysis for the supplemental proposal used the Class 

lib and Class VI HDGV breakdown where it was possible. 

However, to calculate incremental costs for improved 

evaporative systems, the Class lib and Class VI values had to 

be weighted into single-tank HDGVs and dual-tank HDGVs. This 

weighting was based on the ratios used in the original onboard 

analysis. Since Class lib and Class VI represent 75 and 25 

percent of the HDGV fleet, weighting the previously stated 

single and dual tank percentages by class implies that 81 

percent of HDGVs are single tank while 19 percent are dual 

tank. Of the single-tank HDGVs, 74 percent are Class lib while 

26 percent are Class VI. Of the dual-tank HDGVs, 79 percent 

are lib while 21 percent are Class VI. 

2. Canister Cost 

The analysis of the improved evaporative and revised 

onboard projected systems utilized the new canister sizing 

model and typical fuel tank sizes. The purge rate used was 20 

cubic feet per LA-4 for LDVs and LDTs, and 18 cubic feet per 

chassis cycle for HDGVs. The fuel tank sizes, which affect 

canister size, were the same as those used in the original 

proposal. 

the model used to estimate canister cost as a function of 

canister size is the same as that used in the original 

proposals. Charcoal cost was still estimated to be $1.40 per 

pound.! This value was not inflated due to a current price 

range of $1.00 to $1.50 given by charcoal manufacturers. The 

costs used in estimating the canister shell were increased by 

15.8 percent to account for inflation. 

Table 5 shows the fuel tank sizes, canister sizes, and 

canister costs for the excess evaporative, improved evaporative 

and revised onboard systems. The incremental costs are also 

shown. All of the values in Table 5 are for 9.0 psi RVP 

certification fuel. Costs for 11.5 psi RVP certification fuel 

are in Table 6 for the excess and improved evaporative 

systems. For the canister size estimates for 11.5 RVP 

certification fuel it was assumed that manufacturers would 

develop fuel cooling systems to reduce vapor generation in 

order to avoid using an even larger canister. The vapor 

generation rate is very large with 11.5 RVP fuel because the 

fuel tank temperatures reached during the revised test 

procedure approach the boiling point of the many lighter 

hydrocarbon components which make up 11.5 RVP fuel, and the 

percentage of lighter hydrocarbon components is greater at 11.5 

RVP than at 9.0 RVP. 
Vehicle* 

LDV 

LDT-S 

LDT-D 

Ilb-S 

Ilb-D 

VI-S 

VI-D 

HDGV-S 

HDGV-D 

Fuel tank 

Size(Gal) 

12.2 

16.3 

Two at 16.3 

20 

Two at 20 

30 

Two at 40 

— 

— 

Revised G 

Canister 

Size(L) 

2.8 

4.1 

4.1 ea 

4.7 

4.7 ea 

7.7 

11.0 ea 

— 

— 

Canister Costs 

inboard System 

Total 

Cost**,***($) 

7.14 

9.47 

18.94 

10.51 

21.01 

15.48 

41.16 

— 

— 

Table 5 

(1988 $), 9.0 psi RVP 

Improved Evaporative Sys 

Canister 

Size(L) 

2.7 

3.9 

3.9 

4.3 

4.3 

7.0 

10.1 

— 

— 

Total 

Cost**,***($! 

6.95 

9.12 

18.24 

9.82 

19.64 

14.36 

38.42 

11.00 

23.58 

Excess Evaporative System 

Canister Total 

Size(L) Cost»*($) 

1.3 3.92 

1.7 4.75 

1.7 9.50 

4.0 

4.0 

9.05 

18.09 

Vehicle* 

LDV 

LDT-S 

LDT-D 

Ilb-S 

Ilb-D 

VI-S 

VI-D 

HDGV-S 

HDGV-D 

Incremental Cost ($), 

Onboard > Improved 

Vendor RPE**** 

0.19 0.23 

0.35 0.44 

0.70 0.88 

0.69 0.87 

1.37 1.74 

1.12 1.42 

2.74 3.48 

Incremental 

Improved 

Vendor 

3.03 

4.37 

8.74 

— . 

— 

— 

— 

Cost ($), 

> Excess 

RPE**** 

3.82 

5.51 

11.02 

— 

— 

— 

— 

1.95 

5.49 

2.48 

6.97 

O N 

I 

* "S" = Single fuel tank. "D" = Dual fuel tanks. 

** Total canister cost . for vehicle. For vehicles with dual tanks, this cost includes both 

canisters (one canister per fuel tank). 

*** The canister costs for revised onboard and improved evaporative systems include an 

additional cost for dust caps ($0.25 per canister for LDVs, LDTs and Class lib HDGVs, $0.30 

for Class VI HDGVs at the vendor level.) 

**** RPE = Retail Price Equivalent (26% markup for LDVs and LDTs, 27% markup for HDGVs). 
Table 6 

Vehicle* 

LDV 

LDT-S 

LDT-D 

Ilb-S 

Ilb-D 

VI-S 

VI-D 

HDGV-S 

HDGV-D 

Fuel tank 

Size(Gal) 

12.2 

16.3 

Two at 16.3 

20 

Two at 20 

30 

Two at 40 

Canister Costs (1988 $), 11.5 psi RVP 

Improved Evaporative System Excess Evaporative System 

Canister 

Size(L) 

9.3 

13.2 

13.2 

13.2 

13.2 

21.0 

29.4 

Total 

Cost**,***($) 

17.94 

23.82 

47.64 

23.82 

47.64 

35.06 

93.15 

26.74 

57.20 

Canister 

Size(L) 

2.1 

2.7 

2.7 

6.4 

6.4 

Total 

Cost**($) 

5.51 

6.71 

13.41 

13.09 

26.17 

Incremental Cost ($) 

Improved > Excess 

Vendor 

12.43 

17.11 

34.23 

13.65 

31.03 

RPE**** 

15.-66-

21.56 

43.13 

17.34 

39.41 

* 

** 

"S" = Single fuel tank. "D" = Dual fuel tanks. 

Total canister cost for vehicle. For vehicles with dual tanks, this cost includes both 

canisters (one canister per fuel tank). 

*** The canister costs for revised onboard and improved evaporative systems include an 

additional cost for dust caps ($0.25 per canister for LDVs, LDTs and Class lib HDGVs, $0.30 

for Class VI HDGVs at the vendor level.) 

**** RPE = Retail Price Equivalent (26% markup for LDVs and LDTs, 27% markup for HDGVs). 

i 

00 
P.19 

-18-

Dust caps were added to LDV and LDT canisters because it 

is assumed that they would be located in the rear of the 

vehicle, making them more prone to dirt from the road. The 

cost of these dust caps was estimated to be $0.25 per canister 

at the vendor level. Although HDGV canisters are assumed to 

remain in their present location in the engine compartment, 

dust caps were added in order to make a conservative cost 

estimate. These dust caps were estimated to cost $0.30 per 

canister at the vendor level. 

3. Vapor Lines 

The vapor lines are used to route fuel vapors between the 

fuel tank, canister, engine, etc. In the original onboard 

proposal, EPA assumed that all vapor lines were made of 

epichiorohydrin (ECO) rubber tubing. With further 

investigation, EPA has learned that manufacturers frequently 

use welded steel tubing with rubber connecting pieces. EPA has 

therefore modified its cost analysis to include steel tubing. 

A vendor provided cost per foot prices for large-scale 

sales of terne coated, welding steel tubing, having a wall 

thickness of 0.028 inches. Values were given to a tenth of a 

cent accuracy for 5/16-inch and 3/8-inch O.D. tubing. Prices 

for other tube sizes were obtained by extrapolating from these 

given prices and then rounding to the nearest penny. The 

results are given below: 

Steel Tubing Vendor Cost (1988 $) 

5/16" I.D. = $0.10/ft. 

3/8" I.D. = $0.11/ft. 

1/2" I.D. - $0.14/ft. 

The costs for rubber tubing were obtained from the 

original onboard proposal with an adjustment made for 

inflation. The costs for 1/2 and 5/16-inch tubing were 

obtained from a graphical curve fit of the l/4-inch, 3/8-inch, 

and 5/8-inch values. The results for the rubber tubing cost 

are given below: 

Rubber Tubing Vendor Cost (1988 $) 

1/4" I.D. » $0.31/ft. 

5/16" I.D. = $0.34/ft. 

3/8" I.D. - $0.37/ft. 

1/2" I.D. = $0.46/ft. 

5/8" I.D. =» $0.58/ft. 

i. External Vent Line 

The external vent line is presently used on vehicles to 

allow vapors to escape from the fuel tank during refueling. 

The use of external vent lines allows for the fillpipe to be 

smaller in diameter since it only needs to handle fuel flow 
P.20 

-19-

instead of fuel and vapor flow. With the control system 

described in the supplemental onboard proposal, refueling 

vapors will be routed out of the top of the fuel tank to the 

onboard refueling canister. Because of this new routing, the 

external vent line will no longer be needed. This line can 

therefore be removed from future vehicles with a corresponding 

cost savings. 

The external vent line for LDVs and LDTs was assumed to 

have a 1/2-inch I.D., be three feet long, and be composed of a 

one-foot long steel midsection and two one-foot long rubber 

connectors on both ends. Clearly there are variations on these 

sizes and this design which could lead to some small cost 

variations. The cost of the external vent line for LDVs and 

LDTs was calculated as follows: 

2' Rubber @ $0.46/ft 

1' Steel @ $0.l4/ft 

4 Clamps @ $0.05 each 

$0 

$0 

$0 

$1 

$1 

92 

14 

20 

26 

.59 

Total 

Markup (by 1.26) $1.59 + $1.60 

For class lib HDGVs, a 1/2-inch I.D., three-foot rubber 

line was assumed. The rubber line allows for more flexibility 

for second-stage manufacturers. The resulting cost was 

calculated as follows: 

3' Rubber @ $0.46/ft = $1.38 

2 Clamps @ $0.05 each = $0.10 

Total $1.48 

Markup (by 1.27) $1.88 + $1.90 

It was assumed that the fillnecks on Class VI HDGVs 

currently have a large enough diameter to allow vapor venting 

without using an external vent line. Therefore there would be 

no cost savings associated with this part. 

ii. Canister Related Vapor Lines 

The canister requires two vapor lines for proper system 

operation: 1) the vapor vent line from the fuel tank to the 

canister for vapor loading, and 2) the purge line from the 

canister to the engine for canister purging. The size (length 

and diameter) of the vapor lines is dependent on the canister 

location, the vapor flow rate, and the allowed pressure drop. 

The cost depends on the size, the material used and the 

construction of the line. EPA expects both the onboard and 

improved evaporative canisters to be located in the rear of the 

vehicle for LDVs and LDTs. Therefore, there will be a short 

vapor vent line between the fuel tank and canister, but a long 

purge line. In comparison, EPA expected excess evaporative 
P.21 

-20-

canisters to be located in the front of vehicles, as they 

typically are for current systems. In this case, the vapor 

vent line between the fuel tank and canister is long, but the 

purge line is relatively short. 

EPA sized the vapor lines for the improved evaporative and 

the revised onboard systems based upon the expected flow rates 

and allowed pressure drops. For LDVs and LDTs, the purge line 

on the improved evaporative system is expected to have the same 

diameter, length, materials and construction as the fuel tank 

vapor vent line of the excess evaporative system. Therefore, 

any difference in vapor line costs between the two systems is 

due to the difference between the improved evaporative fuel 

tank vapor vent line and the excess evaporative purge line. 

They are expected to have the same length, materials and 

construction but the improved evaporative fuel tank vapor vent 

line must be of a larger diameter than the excess evaporative 

purge line. For the onboard system, the improved evaporative 

purge line is expected to be of adequate size for purging the 

onboard canister. Therefore, the only change in vapor line 

costs between the onboard and the improved evaporative system 

results from the need to increase the diameter of the improved 

evaporative fuel tank vapor vent line to be adequate for the 

refueling vapor flow rate. 

For HDGVs, EPA assumed that there is enough space 

available in the engine compartment for improved evaporative 

and/or onboard system canisters. It was also assumed that the 

excess; evaporative system purge line is adequately sized for 

improved evaporative and onboard systems. However, there are 

incremental vapor line costs for improved evaporative and 

onboard systems because larger diameter fuel tank vapor vent 

lines are necessary to handle the greater flow rates of vapors. 

The cost calculations for vapor lines for onboard, 

improved evaporative, and excess evaporative systems are shown 

in Table 7 for LDVs and LDTs, and in Table 8 for HDGVs. For 

LDVs and LDTs, combinations of various diameter steel and 

rubber vapor lines are assumed. For HDGVs all rubber tubing 

was used. Variations in these design approaches are possible 

which would either slightly increase or decrease cost. 

Directionally, more use of steel would decrease costs while 

more use of rubber would increase costs. 
P.22 

-21-

Table 7 

Vendor Level Vapor Line Costs - LDVs and LDTs 

Excess Evap Purge Line - 3ft <3 1/4" 

1 ft Rubber @ $0.31/ft = $0.31 

2 ft Steel a $0.08/ft = 0.16 

Total = $0.47 

Improved Evap Fuel Tank Vapor Vent Line - 3ft § 3/8" 

1 ft. Rubber 0 $0.37/ft = $0.37 

2 ft. Steel (3 0.11/ft = 0.22 

Total = $0.59 

Onboard Fuel Tank Vapor Vent Line - 3ft @ 1/2" 

1 ft. Rubber 0 $0.46/ft = $0.46 

2 ft. Steel Q 0.14/ft = 0.28 

Total = $0.74 
P.23 

-22-

Table 8 

Vendor Level Vapor Line Costs - HDGVs 

Class lib: 

Excess Evap Fuel Tank Vapor Vent Line - 8 ft <§ 3/8" 

8 ft Rubber @ $0.37/ft = $2.96 

Improved Evap Fuel Tank Vapor Vent Line - 8 ft @ 1/2' 

8 ft Rubber <3 $0.46/ft = $3.68 

Onboard Fuel Tank Vapor Vent Line - 8 ft <3 5/8" 

8 ft Rubber § $0.58/ft = $4.64 

Class VI: 

Excess Evap Fuel Tank Vapor Vent Line - 15 ft 0 3/8" 

15 ft Rubber ® $0.37/ft = $5.55 

Improved Evap Fuel Tank Vapor Vent Line - 15 ft 9 1/2" 

15 ft Rubber <§ $0.46/ft = $ 6.90 

Onboard Fuel Tank Vapor Vent Line - 15 ft @ 5/8" 

15 ft Rubber 0 $0.58/ft = $ 8.70 
P.24 

-23-

4. Vapor Vent/Rollover Valve 

Modified vapor vent/rollover valves are needed for both 

the improved evaporative system and the onboard system. Many 

vehicles already have some form of vapor vent/rollover valve. 

However, to make a conservative estimate, EPA did not subtract 

the cost of any existing valve from the cost of the modified 

valve when considering the incremental costs for improved 

evaporative and revised onboard systems. 

The valve required for the improved evaporative system 

must allow fuel tank vapors to be vented to the canister and 

must also close the venting orifice during vehicle rollover. 

The valve may also have an orifice sealing device which is 

bouyant in gasoline (a float) that would protect the vapor line 

from sloshing fuel. This float probably will not need to 

perform a fill limiting function since the orifice of the valve 

should be small enough to create sufficient backpressure to 

cause the automatic dispensing nozzle to shutoff. This vapor 

vent/rollover valve is mounted in the top of the fuel tank. 

The onboard system valve will have a larger diameter 

venting orifice in order to handle refueling vapor flow rates, 

with this larger diameter orifice, the back pressure in the 

tank will probably not be sufficient to cause automatic nozzle 

shutoff. The valve will need a fill limiting float which 

closes off the venting orifice when the tank is full and 

thereby creates enough backpressure in the tank to cause the 

nozzle to shutoff. The float would also provide fuel sloshing 

protection for the valve. Because the main orifice of the 

onboard valve is closed when the tank is full, a small 

secondary evaporative orifice is necessary in order to allow 

tank venting at that fill level. This secondary orifice only 

needs to be about the size of some current evaporative orifices 

which is 0.05 inches in diameter. Any improved evaporative 

system valves which have fill-limiting functions would also 

need this secondary orifice. 

EPA contacted a vendor concerning valve design and 

expected cost. This vendor presently sells existing 

vent/rollover valves for just under three dollars. The 

existing valve configuration is expected to be adequate for the 

improved evaporative system (with a slightly larger orifice -

no change in material cost). There is no cost associated with 

making the valve closure device bouyant (to accomplish fill 

limiting and/or to provide fuel sloshing protection). Many 

evaporative system valves currently have bouyant shutoff 

devices. Those that don't could switch from one closure 

mechanism, such as ball bearings, to a float. This would not 

cause an increase in cost and in fact may be less expensive. 

EPA therefore allocated a $3.00 manufacturer cost to the 

improved evaporative system valve. 

The onboard system valve has a slightly larger diameter 

orifice, a buoyant float and the additional secondary orifice. 

There is no change in cost due to the larger orifice or the 
P.25 

-24-

bouyant float. However the cost of adding the secondary 

orifice is estimated to be about $0.50 at the manufacturing 

level. The vapor vent valve for the refueling system is thus 

expected to have a manufacturing cost of $3.50 at high volume 

production. Tables 3 and 4 show these costs in RPE with the 

appropriate markup. 

5. Anti-Spitback Valve 

A liquid seal based onboard system such as that discussed 

in the; supplemental notice may require an anti-spitback valve 

to prevent fuel from "spitting" back out of the fillneck at 

automatic nozzle shut-off during vehicle refueling. Some 

manufacturers are already incorporating these valves in some of 

their vehicle models. This will provide an additional safety 

feature for onboard systems over present systems. A vendor 

quoted1 the valve cost at 25 cents plus tooling. Estimating the 

tooling cost at 3 cents and adjusting for markup, EPA estimates 

that the valves will cost 35 cents each. These costs are shown 

in Table 4. 

6i. Seal Assembly 

Onboard systems require some type of seal to prevent 

vapors from escaping out the fillneck during vehicle 

refueling. LDVs, LDTs, and Class lib HDGVs typically have 

small diameter fillnecks of adequate length to provide a liquid 

seal during refueling. Therefore, no cost was allocated for 

seal hardware. However, Class VI HDGVs have several different 

fuel tank arrangements. Some of these fuel tanks have no 

fillneck, some have short fillnecks and some have large 

diameter fillnecks. The sealing mechanism for these tanks may 

vary depending on design and location constraints. However, 

EPA believes that manufacturers will use the least expensive 

method1 possible to provide an adequate seal and is therefore 

using the same value as was developed in the original proposal 

(adjusted for inflation), without identifying a specific seal 

design. EPA expects that many different approaches could be 

used, but none that would be more expensive than the previous 

estimate for a seal assembly consisting of a mechanical seal 

and a pressure relief device. 

7. Purge Valve 

In the original volatility proposal, for each vehicle 

class EPA estimated the average cost of improved purge valves 

which would be needed to handle the higher purge rate necessary 

for excess evaporative systems. EPA assumed that the improved 

valve would be a frequency modulated solenoid operated by the 

ECU. The full cost of the valve for excess evaporative systems 

incremental to current evaportive systems was calculated to be 

$0.96 in 1986 dollars at the manufacturer level ($1.30 in RPE, 

1988 dollars). EPA expected that only carbureted vehicles 

would need the improved valve if 9.0 RVP fuel was used, but 

that all vehicles would need it if 11.5 RVP fuel was used. 

Therefore at 9.0 RVP only the fraction of the full cost of the 
P.26 

-25-

valve which was equivalent to the fraction of carbureted 

vehicles predicted to be in the fleet in 1990 was calculated as 

an average fleet cost ($0.18 at the manufacturer level in 1986 

dollars, $0.25 RPE in 1988 dollars). The full cost of the 

valve was assumed for every vehicle at 11.5 RVP. 

EPA believes that this same frequency modulated solenoid 

valve will be adequate for both improved evaporative and 

onboard systems. However, it is expected that these systems 

will require the improved valve on all vehicles at 9.0 RVP 

instead of just on carbureted vehicles. Therefore the only 

purge valve cost for improved systems incremental to excess 

evaporative systems is due to allocating the full cost of the 

valve to all vehicles at 9.0 RVP. There is no incremental cost 

at 11.5 RVP. There is also no cost for onboard systems 

incremental to improved evaporative systems for this component, 

since the same purge valve would be used. 

8. Fuel Cooling System 

For improved evaporative systems, it appears that if 11.5 

RVP fuel is used some type of cooling mechanism may be required 

for the fuel return line in order to reduce the amount of 

vapors being generated in the fuel tank during vehicle 

operation. This might be achieved by adding cooling fins to 

the return line along with air ducting or through some other 

means. EPA estimated the manufacturer's cost for this 

mechanism (or some other similar approach) to be approximately 

five dollars. 

B. Development Costs 

Development costs are all costs other than component 

hardware which factor into the final retail price equivalent 

(RPE) of the vehicle. These costs are associated with fuel 

tank modifications, vehicle packaging, assembly, certification, 

facility modifications and systems engineering. The 

development costs used in this analysis are all based upon 

short-term (0 to 5 years) costs to the manufacturer. These 

costs are recovered by the manufacturer after 5 years (except 

for the cost of facility modifications, which is recovered 

after 10 years). If a long-term cost analysis were done 

(greater than 5 years), then the net cost of each system would 

decrease and the cost effectiveness would increase. 

Development costs were calculated for both the .original 

volatility (excess evaporative systems) and the original 

onboard proposals. The following discussion explains any 

changes in these costs associated with the improved evaporative 

and revised onboard systems detailed in the SNPRM. Improved 

evaporative system development costs are shown as incremental 

to excess evaporative costs and onboard costs are shown as 

incremental to improved evaporative costs. 
P.27 

-26-

1. Improved Evaporative Systems 

In the original volatility proposal, the non-hardware 

category included costs for certification and research, 

development, and testing (RD&T). Table 9A summarizes the 

additional developmental (non-hardware) costs due to improved 

evaporative systems. All values are in retail price 

equivalents and are rounded off to the nearest nickel. Each of 

these values are explained below. 

Packaging costs arise when hardware or vehicle 

modifications must be made in order to accommodate new 

components or an increase in the size of old components. In 

the original volatility proposal, EPA assumed that no body 

modifications would need to be made to accommodate excess 

evaporative systems and that no packaging costs would be 

incurred. Some packaging costs may arise for improved 

evaporative systems on LDVs and LDTs due to the increased size 

of the canister, which EPA expects to be rear-mounted. EPA 

estimates the amortized cost (over 5 years) to manufacturers to 

be $0.60 per vehicle per canister. There are no space 

constraints on HDGVs which result in an increased packaging 

cost. However, many Class lib vehicles are modified by 

secondary manufacturers who may incur an added cost to handle 

the new systems. Therefore, an added cost of $0.65 at the 

manufacturer level was added for single tank Class libs and 

$1.35 for dual tank Class libs. Although secondary 

manufacturers do not modify many Class VI HDGV vehicle fuel 

systems, packaging costs equal to those on Class libs were 

added in order to make a conservative estimate. The values 

shown in Table 9A reflect the appropriate RPE markup values for 

LDVs, LDTs and HDGVs. 

EPA did not allocate an additional cost to improved 

evaporative systems for RD&T. Costs were previously allocated 

to excess evaporative systems and include the cost of vehicle 

acquisition, engineers and technicians salaries and testing 

costs. Since manufacturers will be developing one evaporative 

system per vehicle family (rather than an improved system in 

addition to an excess system) no additional cost was needed. 
Table 9A 

Improved Evaporative System Development Costs* (in RPE, 1988$) 

Item Vehicle/Certification Fuel 

LDV 

9.0RVP 11.5RVP 

LDT-S 

9.0RVP 11.5RVP 

LDT-D 

9.0RVP 11.5RVP 

HDGV-S 

9.0RVP 11.5RVP 

HDGV-D 

9.0RVP 11.5RVP 

Packaging 0.75 0.75 0.75 0.75 

«*_-**• 0.00 0.00 0.00 0.00 

Certification*** 0.05 0.05 0.05 0.05 

1.50 

0.00 

0.05 

1.50 

0.00 

0.05 

0.85 

0.00 

0.05 

0.85 

0.00 

0.05 

1.70 

0.00 

0.05 

1.70 

0.00 

0.05 

Total $0.80 $0.80 $0.80 $0.80 $1.55 $1.55 $0.90 $0.90 $1.75 $1.75 

* Costs are incremental to those expected for excess evaporative control. These costs only apply for 5 years. 

** Cost previously allocated to Excess Evaporative System. 

*** Cost to add two diurnals and cap removal to FTP. 

i 

-J 

oo 
P.29 

-28-

Certification costs increase if there is a need to 

recertify previous model year vehicles in order to comply with 

changed requirements. Certification costs also increase if 

changes to the test procedure make it more resource intensive. 

The original volatility proposal contained a detailed 

description of the analysis done to develop the cost to 

recertify vehicles equipped with excess evaporative control 

systems using 9.0 RVP test fuel. The fraction of vehicles 

which must be recertified is the same whether vehicles are 

equipped with excess or improved evaporative systems. It was 

estimated that 90 percent of engine families are carried over 

from the previous year and so recertification costs were 

applied to 90 percent of the fleet. Since the original 

proposal, EPA has learned that while a 90 percent carryover may 

be a good estimate for durability vehicles, the fraction of 

emission data vehicles which are carried over is closer to 10 

percent. This makes EPA's estimate conservative, since only 10 

percent of those vehicles would actually need to be 

recertified. Refining the estimate at this time would not have 

a large impact on the total cost since the certification cost 

is such a small fraction of it. This change, along with other 

improvements in the estimates, will be made at the time of the 

final rule. 

The cost for certification (or recertif ication) test of 

vehicles with improved evaporative systems is greater because 

of the two diurnals which have been added to the test procedure 

for separate systems. The two diurnals result in an additional 

0.35 Federal Test Program Equivalents (FTPEs) plus the cost of 

fuel for two additional fills to the 40 percent level. The 

additional certification cost was calculated based upon many of 

the same assumptions as were used in the original volatility 

proposal. One significant change is that the number of tests 

per HDGV family was reduced from 50 in the original volatility 

proposal to 10. This is because the 50 tests in the original 

proposal actually included some tests for research and 

development rather than certification. 

Unlike the recertification cost calculation of the excess 

evaporative proposal which applied to only 90 percent of the 

fleet, the increase in certification cost applies to the entire 

fleet. Since certification is done approximately one year 

before the vehicles can be sold, costs were increased by 10 

perceiit to account for the item value of money. The cost 

calculations for LDVs and LDTs are shown in Table 9B while the 

calculations for HDGVs are shown in Table 9C. The additional 

cost per vehicle in RPE rounded to the nearest nickel is $0.05 

for LDVs, LDTs, and HDGVs. 
P.30 

•29-

Table 9B 

Incremental Certification Cost 

for Improved Evaporative Systems 

(LDVs, LDTs) 

LDV LDT 

Cost of FTPE 650 650 

1986 Dollars ' 

(From 1987 Volatility RIA) 

Cost of FTPE : 701 701 

1988 Dollars 

Cost of 2 Refuelings at 12.2 gal tank "* $8.00 16.3 gal tank (80S Single, 

40% fill ($6.82/gallon) 20% Dual) "* $12.30 

Additional Cost per Test $253.30 257.65 

= 0.35(FTPE) • Fuel Cost 

Durability Vehicle Tests: 109 Vehicles/year 45 vehicles/year 

x 13 tests/vehicle x 13 tests/vehicle 

x $253.30/test x $257.65/test 

$359 K $151 K 

Additional Cost for 

Emission Data Vehicle Tests: 307 Vehicles/year 133 vehicles/year 

x 2 test/vehicle x 2 tests/vehicle 

x £253.30/test x $257.65/test 

-$156 K -$ 69 K 

Sum of Durability and 

Emissions Data Cost: $515 K $220 K 

Add 10% for 1 year time 

Value of money $567 K $242 K 

Amortize over 5 years at 10%: $150 K $ 64 K 

(Amortization factor = 0.2638) 

Sales projection: 11.2 million 3.64 million 

Cost/Vehicle: SO.01 $0.02 

Cost/Vehicle in RPE 

Rounded to nearest nickel: 30.05 $0.05 
P.31 

-30-

Table 9C 

Incremental Certification Cost 

for Improved Evaporative System (HDGVs) 

Cost of FTPE: $620 

1986 Dollar^ 

(From 1987 Volatility RIA) 

Cost of FTPE: $667 

1988 Dollars 

Calculate Average 

HDGV Fuel Tank Size: 

Cost of 2 Refuelings 

at 40% fill 

($0.82/gal) 

Additional Cost per Test 

= 0.35 (FTPE) • Fuel Cost 

Total Additional Cost 

Add 10% for 1 year time: 

Value of money 

lib: Single: 20 gal. Dual: 2 9 20 gal. 

lib: Weighted: (0.80)(20 gal) • 

(0.20H40 gal) = 24 gal. 

VI: Single: 30 gal. Dual: 2 9 40 gal. 

Weighted: (.85)(30 gal) • 

(.15)(80 gal) = 37.5 gal. 

Avg HDGV Tank Size = (0.75)(24 gal) • 

(0.25)(37.5 gal) = 27.4 gal. 

$18.00 

$251 

($251/test)(10 tests/family)(23 families) = $58 K 

$64 K 

Amortize over 5 years at 10% $17 K 

(Amortization factor = 0.2638) 

Sales Projection: 386,000 vehicles 

Incremental Cost per Vehicle: $0.04 

Cost per vehicle in RPE 

Rounded to Nearest Nickel: $0.05 
P.32 

-31-

2. Onboard System 

In the original onboard proposal, the non-hardware 

category included costs for fuel tank modifications, packaging, 

assembly, certification, facility modifications, and systems 

engineering. These costs must be changed since the onboard 

system design has been revised and since only the cost 

incremental to improved evaporative system development costs 

are now allocated to the onboard system. Table 10 summarizes 

the present development costs. All values are in retail price 

equivalents and rounded off to the nearest nickel. Each of 

these values are explained below. 

With the development of a simpler onboard system and with 

the changes made in the evaporative proposal, the costs for 

fuel tank modifications and for assembly no longer apply. The 

fuel tank is no longer being modified for a J-tube and fill 

limiter. The onboard vapor/rollover valve may require a 

slightly larger hole in the fuel tank than that required for 

the evaporative vapor/rollover valve but this is not expected 

to result in a cost increase. Therefore, no cost was allocated 

for fuel tank modifications. 

The original assembly cost considered the additional cost 

to install the onboard canister in separate systems since it 

was thought that carbureted vehicles might have separate 

systems so that the evaporative canister could be located near 

the carburetor while the refueling canister would be located 

near the fuel tank. This would minimize the size and length of 

the vapor and purge lines. However, since EPA is proposing to 

keep certification fuel at 9.0 psi RVP, onboard canisters would 

be smaller than originally estimated. In addition, nearly all 

vehicles will be fuel-injected by the time onboard systems are 

required. The most important change since the original onboard 

proposal is that improved evaporative system canisters would be 

nearly as large as integrated evaporative and refueling 

canisters. This makes integrated systems much more attractive 

than separate systems since less total canister volume and 

fewer connective parts are necessary. There is, therefore, no 

additional assembly cost for installing onboard systems 

incremental to that for improved evaporative systems. 

Most of the packaging cost of an integrated onboard 

canister is already allocated to the improved evaporative 

system costs. However, some vehicle models may require 

additional body modifications for the slightly larger onboard 

canister. EPA estimates this cost to have an amortized value 

(over 5 years) of 10 cents per vehicle per canister (in RPE). 

No cost was allocated for Class VI HDGVs due to their large 

size and additional available space. Costs were conservatively 

assigned to Class lib HDGVs, even though in many cases adequate 

space would be available. 
P.33 

-32-

Table 10 

Onboard System Development Costs* (in RPE, 1988 $) 

Vehicle 

Item LDV LDT-S LDT-D Ilb-S Ilb-D VI-S VI-D 

Tank Mods $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 

Assembly 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

Packaging 0.10 0.10 0.20 0.10 0.20 0.00 o.oo 

Recertification 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

Facility Mods** 0.45 0.45 0.45 0.45 0.45 0.45 0.45 

Systems Engr** 0.50 0.80 1.10 0.80 0.80 1.75 1.75 

Total $1.05 $1.35 $1.75 $1.35 $1.45 $2.20 $2.20 

* Costs are incremental to those expected for excess and improved 

evaporative control. These costs only apply for 5 years, except for 

the facility modifications cost which applies for 10 years. 

** Same values as in original proposal, adjusted for inflation. 
P.34 

-33-

The recertification costs for onboard systems are 

essentially zero incremental to those expected with 

improved/excess evaporative control. EPA expects the onboard 

and evaporative regulations to have the same effective dates. 

Since recertification costs have already been allocated to 

excess evaporative systems, no additional cost is needed here. 

EPA also did not include an additional certification cost for 

the onboard test procedure. The additional procedure for 

integrated systems will be in lieu of the additional diurnals 

for the improved evaporative systems on separate 

refueling/evaporative systems. Since an additional 

certification cost was included there, none is included for the 

integrated onboard systems. 

EPA did not re-evaluate the cost for facility 

modifications for the supplemental proposal. The value used in 

the original onboard proposal was adjusted for inflation only, 

resulting in a 45 cent per vehicle cost (in RPE) when amortized 

over a ten year-period. EPA also did not re-evaluate the 

systems engineering costs other than to adjust it for 

inflation. These costs were amortized over 5 years. However, 

since ; the system has been simplified, the original cost is 

probably conservative. 
P.35 

-34-

C. Recovery Credits 

The following discussion on recovery credits (weight 

penalty and fuel recovery) is specific for each system. A net 

recovery credit has two components: a fuel recovery credit and 

a weight penalty. The fuel recovery credit accounts for the 

fuel that is saved when fuel vapors are captured by a vapor 

recovery system and utilized. The weight penalty accounts for 

a loss in fuel economy due to the slight increase in vehicle 

weight! added by the vapor recovery system. The net recovery 

credit is the difference between the money saved from fuel 

recovery and the increased fuel consumption cost to move a 

slightly heavier vehicle. The recovery credits for excess 

evaporative systems will be discussed first. Recovery credits 

for improved evaporative systems and onboard systems will 

follow. 

1. Excess Evaporative System 

There was no weight penalty associated with the excess 

evaporative system of the original volatility proposal since 

there were no changes necessary in vehicle hardware at 9.0 RVP 

fuel which would result in a weight penalty. The fuel recovery 

credit for these systems is a function of not only changes to 

the vehicle control system but also of change in commercial 

fuel volatility (both the matching of in-use and certification 

fuel RVP and the RVP level at which this is done). The portion 

of the excess evaporative fuel recovery credit due solely to 

vehicle controls is difficult to determine. Also, if the 

excess evaporative fuel recovery credit is included, then the 

increase in lifetime fuel cost to the vehicle owner due to 

commercial fuel volatility control must also be included. 

Since |the purpose of this analysis is only to determine vehicle 

controjl system costs and not volatility control costs, the 

excess evaporative fuel recovery credit was not included here. 

2f. Improved Evaporative Systems 

The net recovery credits for the improved evaporative system 

were Calculated for 9.0 psi RVP fuel. The weight penalty will 

be discussed first. 

(i) Weight Penalty 

The weight penalty for the improved evaporative system was 

calculated using the same method as was used in the original 

onboard proposal. The components which were included in the 

weight calculation are the canister, vapor lines, and the vapor 

vent/rollover valve. A carbon density of 0.66 lb./L. and a 

body weight of 0.445 pounds for a 1.5 liter canister are the 

same values used in the original onboard proposal. The body 

weight of other cylindrical canister sizes is assumed to be 

proportional to the ratio of the squares of the canister 
P.36 

-35-

radii. (The square of the radius for a 1.5 L canister, 

assuming the height to be equal to the diameter, is 38.5 

cm2). Tables 11A and H B show the calculations for the 

change in canister weights between the improved and excess 

evaporative systems. The calculations showing the change in 

weight due to the increased diameter of the vapor lines are 

shown in Tables 12A and 12B. There is no difference in weight 

between the improved evaporative vapor vent/rollover system 

valve and the revised onboard system valve. Also, EPA did not 

subtract the weight of any possible current system vent valve 

from that of the improved evaporative valve so that the full 

valve weight was allocated to the improved evaporative system. 

The same weight was used as that which was measured for the 

valve on the original onboard proposal system. This is a 

conservative estimate since the original onboard valve was a 

heavier fillneck mounted valve made of steel while the improved 

evaporative valve is plastic and mounted on the tank. The 

values below have been weighted by sales for single and dual 

fuel tanks. 
LDVs 

Table 11A 

Evaporative System Canister Weights 

9.0 psi RVP fuel. 

Canister Carbon + 

Size Weight 

System 1.3 L 0.9 lbs. 

re System 2.7 L 1.8 lbs. 

, LDVs and LDTs; 

Canister Body = 

Material Weight 

0.4 lbs. 

0.7 lbs. 

Total Canister 

Weight 

1.3 lbs. 

2.5 lbs. 

Incremental Canister Weight 

for Improved Evaporative System 1.2 lbs. 

LDTs 

Single Tank 

Excess Evaporative System 1.7 L 

Improved Evaporative System 3.9 L 

1.1 lbs. 0.5 lbs. 1.6 lbs. 

2.6 lbs. 0.8 lbs. 3.4 lbs. 

Incremental Canister Weight 

for Improved Evaporative System 1.8 lbs. 

Dual Tank 

Excess Evaporative System 2 § 1.7 L 

Improved Evaporative System 2 § 3.9 L 

2.2 lbs. 1.0 lbs. 3.2 lbs. 

5.2 lbs. 1.6 lbs. 6.8 lbs. 

Incremental Canister Weight 

for Improved Evaporative System 3.6 lbs. 

i 

to 

ON 

I 

LDT Weighted (single and dual) = (80%)(1.8 lbs.) +(20%)(3.6 lbs) =2.2 lbs. 
Table 11B 

Evaporative System Canister Weights, HDGVs; 

9.0 psi RVP fuel. 

Canister Carbon + Canister Body = Total Canister 

Size Weight Material Weight Weight 

Excess Evaporative System 4.0 L 2.6 lbs. 0.9 lbs. 3.5 lbs. 

(From Original Volatility 

Proposal. Average of all 

HDGV classes, and both 

single and dual tanks) 

Improved Evaporative System 

Class lib 

Single Tank 4.3 L 2.8 lbs. 0.9 lbs. 3.7 lbs. 

Dual Tank 2 § 4.3 L 5.6 lbs. 1.8 lbs. 7.4 lbs. 

Weighted (Single and Dual) = (80%)(3.7 lbs) + (20%)(7.4 lbs) = 4.4 lbs. 

Class lib Incremental Canister Weight 

for Improved Evaporative System =4.4-3. 5 =0.9 lbs. i 

Class VI 

Single Tank 7.0 L 4.6 lbs. 1.2 lbs. 5.8 lbs. 

Dual Tank 2 @ 10.1 L 13.4 lbs. 3.2 lbs. 16.6 lbs. 

Weighted (Single and Dual) = (85%)(5.8 lbs.) + (15%)(16.6 lbs) = 7.4 lbs. 

Class VI Incremental Canister Weight 

for Improved Evaporative System =7.4-3. 5 =3.9 lbs. 

I 
P.39 

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Table 12A 

Improved Evaporative System Vapor Line Weights; LDVs and LDTs 

Net incremental weight of the improved evaporative system vapor 

lines is the difference in weight between the 3/8" I.D. fuel 

tank vapor vent line on the improved evaporative system and the 

1/4" I:D. purge line on the excess evaporative system. 

Excess Evaporative 

Purge Line 

2;ft. of 1/4" I.D. Steel: 2 ft, 

1 ft. of 1/4" I.D. Rubber: 1 ft, 

X 0.06 lb/ft 

X 0.08 lb/ft 

0.12 lb 

0.08 lb 

0.20 lb 

Improved Evaporative 

Fuel Tank Vent Line 

2 ft. of 3/8" 

1 ft. of 3/8" 

I.D. Steel: 

I.D. Rubber 

2 ft. X 0.12 lb/ft 

1 ft. X 0.12 lb/ft 

0.24 lb 

0.12 lb 

0.36 lb 

Total Incremental Weight LDVs and LDT Single Tank 

0.36 lb - 0.20 lb - 0.2 lbs. 

Total Incremental Weight LDT Dual Tank 

(80%)(0.20 lb) + (20%)(0.40 lb) - 0.2 lbs. 
-39-

Table 12B 

Improved Evaporative System Vapor Line Weights; HDGVs 

Net incremental weight of the improved evaporative system vapor 

lines is the difference in weight between the 1/2" I.D. rubber 

fuel tank vapor vent line on the improved evaporative system 

and the 3/8" I.D. rubber fuel tank vapor vent line on the 

excess evaporative system. 

Excess Evaporative System 

Fuel Tank Vapor Vent Line 

Class lib: Single Tank 3/8": 

Dual Tanks : 

Class VI: Single Tank 3/8": 

Dual Tanks : 

8 ft. X 0.12 lb/ft. = 0.96 lbs. 

2 X single = 1.92 lbs. 

15 ft. X 0.16 lb/ft. =1.8 lbs 

2 X single =3.6 lbs 

Improved Evaporative System 

Fuel Tank Vapor Vent Line 

Class lib: Single Tank 1/2" 

Dual Tanks 

Class VI: Single Tank 1/2": 

Dual Tanks : 

8 ft. X 0.16 lb/ft. = 1.28 lbs, 

2 X single =2.56 lbs, 

15 ft. X 0.16 lb/ft. = 2.40 lbs 

2 X single =4.80 lbs 

Total Incremental Weight of Vapor Lines 

Class lib: Single Tank: 1.28 lbs. - 0.96 lbs. 

Dual Tank : 2.56 lbs. - 1.92 lbs. 

Weighted: (80%)(0.32) + (20%)(0.64) 

Class VI: Single Tank: 2.4 lbs. - 1.8 lbs. 

Dual Tank 4.8 lbs. - 3.6 lbs. 

Weighted: (85%)(0.6) + (15%)(1.2) 

0.32 lbs 

0.64 lbs 

0.40 lbs 

0.6 lbs. 

1.2 lbs. 

0.7 lbs. 
-40-

P.41 

Vapor Vent/Rollover Valve Weight 

LDV 

LDT: 

HDGV lib: 

HDGV VI: 

(80%)(0.4) +(20%)(0.8) 

(80%)(0.4) + (20%)(0.8) 

(85%)(0.4) + (15%)(0.8) 

0.4 lbs 

0.5 lbs 

0.5 lbs 

0.5 lbs 

The total change in vehicle weight and the corresponding 

effect on fuel economy can now be calculated. The same format 

as that used in the original onboard proposal was used. 

Component LDV LDT lib VI 

Canister (Carbon, Body) 

Vapor Lines 

Valve 

Total Weight (lbs) 

Weight: Multiplication 

Factor (1.1) 

Ave. Vehicle Weight (lbs) 

Percent Change in Weight 

Sensitivity Factor 

(dimensionless) 

Percent Change in Fuel 

Economy (mpg) 

Projected Fuel 

Economy (mpg) 

Projected Avg. Life (miles) 

1.2 lbs 

0.2 

0.4 

1.8 

2.0 

3,082 

0.064% 

-0.329 

-0.021% 

24.61 

100,000 

2.2 lbs 

0.2 

0.5 

2.9 

3.2 

3,832 

0.083% 

-0.402 

-0.033% 

18.43 

120,000 

0.9 lbs 

0.4 

0.5 

1.8 

2.0 

9,250 

0.021% 

-0.402 

-0.009% 

11.16 

110,000 

3.9 lbs 

0.7 

0.5 

5.1 

5.6 

22,500 

0.025% 

-0.402 

-0.010% 

6.07 

110,000 

Lifetime Fuel Consumption 

(gal) 4,063 

Lifetime Weight Penalty 

(gal) 0.9 

6,511 

2.2 

9,857 

0.8 

HDGVs (weighted) = 

18,122 

1.8 

l.l gal 

The total weight penalty cost over the lifetime of the 

vehicle can now be calculated using the same discount factors 

and yearly fuel recovery fractions as used in the original 

onboard proposal. A fuel price of $0.82 per gallon is used, 

which is the same as was used in the original volatility 

proposal. This price does not include taxes and is based upon 

a crude oil price of $20 per barrel. The resulting weight 

penalty is: $0.48 for LDVs, $1.16 for LDTs, and $0.60 for 

HDGVs. 
P.42 

-41-

(i|i) Fuel Recovery Credit 

The fuel recovery credits ($ per vehicle lifetime) are 

based on the emission factor reductions (grams HC per mile) 

resulting from improved evaporative control systems. These 

emission factor reductions, shown in Table 13, were taken from 

a recent EPA analysis.[5] It was assumed that 80 percent of 

current running loss emissions would be controlled by the 

implementation of improved evaporative controls. The total 

emission factor reductions for each vehicle type were then 

multiplied by their expected lifetime mileages discounted at a 

rate of 10 percent (65420 for LDVs, 80932 for LDTs and 71715 

for HDVs) to yield total discounted lifetime emission 

reductions. These emission reductions (assumed to be all 

butane) were then valued at $290.32 per ton based on work 

performed in the original volatility control proposal. (This 

assumes a cost per gallon of gasoline of $0.82 and a combustion 

efficiency of the hydrocarbon vapor equivalent to that of 

liquid fuel; i.e., an evaporative recovery factor of 1.0.) The 

fuel recovery credits on a vehicle lifetime basis are then: 

Vehicle Type 9 RVP Fuel 11.5 RVP Fuel 

LDV $12.31 $42.83 

LDT $20.67 $63.35 

HDV $38.74 $96.07 

The decrease in the credit with 9 RVP fuel results from the 

fact that a great deal of evaporative emission reductions occur 

as a result of volatility control. These volatility-related 

emission reductions are not reflected in the calculations above. 

The net recovery credit for the improved evaporative 

system of each vehicle type is the difference between the fuel 

recovery credit and the weight penalty for that system. These 

values are shown in Table IB. 

3. Onboard System 

The net recovery credits used in the original onboard 

proposal were adjusted to account for the changes made in the 

supplemental proposal. Since the fuel tank sizes and fuel* 

economies did not change in the reproposal, the quantity of 

fuel recovered was not changed. However, the simplified system 

has fewer components than before and even results in the 

removal of the external vent line for LDVs, LDTs and Class lib 

HDGVs. The canister is only slightly larger than the canister 

proposed for the enhanced evaporative system. Therefore, EPA 

considers the weight penalty of onboard systems incremental to 

improved evaporative systems to be essentially zero. In fact, 

there could be a slight weight decrease. 
P.43 

-42-

Table 13 

Emission Factor Reductions Resulting 

From Improved Evaporative Controls[5] 

9 RVP Fuel 

LDV LDT HDV 

High Temperature Diurnal 

Evaporative Emissions (g/mi) 0.34 0.55 1.44 

Running Losses (g/mi) 0.248 0.248 0.248 

Total Emission Factor (g/mi) 0.588 0.789 1.688 

Discounted Lifetime 

Emissions (kg) 38.5 64.6 121.0 

11.5 RVP Fuel 

LDV LDT HDV 

High Temperature Diurnal 

Evaporative Emissions (g/mi) 0.67 1.07 2.81 

Running Losses (g/mi) 1.376 1.376 1.376 

Total Emission Factor (g/mi) 2.046 2.446 4.186 

Discounted Lifetime 

Emission (kg) 133.0 198.0 300.2 
P.44 

-43-

Since there is no weight penalty, the net recovery credit 

is based solely on the fuel recovery credit. The fuel cost was 

adjusted from $0.98/gal to $0.82/gal in order to be consistent 

with the value used in the original volatility proposal. The 

discount factors and yearly fuel recovery fractions used in the 

original proposal were also applied in this analysis. The fuel 

recovery credits for 9.0 psi RVP fuel are shown in Table 14, 

along with the quantity of fuel saved during the vehicle's 

life. These credits are also shown in Table 1C. 
P.45 

-44-

Table 14 

Fuel Recovery Credits for Onboard Systems* 

9.0 psi RVP 

Fuel Savings 

Vehicle (gal/life) (1988$) 

LDV 7.8 $4.20 

LDT 12.6 6.65 

HDGV 23.6 12.60 

Values less than $10 were rounded off to the nearest 

nickel. Values greater than $10 were rounded off to the 

nearest dime. 
-45-

Summary 

i 

The cost analysis for the supplemental proposal for 

improved evaporative and onboard systems were changed only 

where necessary to reflect new requirements, changes in design 

concepts and improved modeling. Components and other cost 

areas not affected were only adjusted for inflation so that all 

values, are in 1988 dollars. The resulting cost estimates 

represent "typical" vehicles. The actual cost for individual 

models will vary. A summary of the costs for excess 

evaporative, improved evaporative and revised onboard systems 

is presented in the following paragraphs. These system costs 

were shown in Tables 1A through ID. 

The estimated net costs for excess evaporative systems 

incremental to current evaporative systems when 9.0 RVP fuel is 

used are $1.45, $1.85 and $3.35 for LDVs, LDTs and HDGVs 

respectively. These costs are entirely due to vehicle cost 

increases since there is no incremental weight penalty and the 

fuel recovery credit can not be included in this analysis for 

reasons already explained. However, this is conservative since 

some of the recovery credit is attributable to vehicle 

charges- The sales weighted net incremental cost for excess 

evaporative systems is $1.60 in RPE. 

The estimated cost for improved evaporative systems 

incremental to excess evaporative systems is $9.65, $13.40, and 

$11.25 for LDVs, LDTs, and HDGVs, respectively, for 9.0 psi RVP 

certification fuel. If the net recovery credits are included, 

the improved evaporative systems should result in a net 

incremental savings of $2.15, $6.10 and $26.90 for LDVs, LDTs 

and HDGVs respectively. The net savings weighted by vehicle 

class is $3.70. 

The estimated cost for simplified onboard systems 

incremental to improved evaporative systems is $0.90, $1.50, 

and $5.20 for LDVs, LDTs, and HDGVs respectively (for 9.0 psi 

RVP certification fuel). If the net recovery credits are 

included, the onboard systems should result in a net savings 

for the vehicle owner. The estimated net incremental savings 

are $3.30, $5.15 and $7.40 for LDVs, LDTs, and HDGVs, 

respectively (9.0 psi RVP). The net incremental savings 

weighted by vehicle class sales is $3.90. 

The total vehicle costs for the onboard refueling and 

evaporative system changes (both excess and improved 

evaporative) are $12.00, $16.75 and $19.80 for LDVs, LDTs and 

HDGVs respectively incremental to current evaporative systems. 

If the net recovery credits are included a net savings is 

realized by the vehicle owner of $4.00, $9.40 and $30.95 in the 

three vehicle classes. The sales weighted net incremental 

savings is $6.00. 
P.47 

-46-

References 

1. Draft Regulatory Impact Analysis, "Control of 

Gasoline Volatility and Evaporative Hydrocarbon Emissions from 

New Motor Vehicles," U.S. EPA, Office of Air and Radiation, 

Office of Mobile Sources, July 1987. Public Docket A-85-22, 

III-B-i. 

2. "Evaluation of Air Pollution Regulatory Strategies 

for Gasoline Marketing Industry - Response to Public Comments," 

U.S. EPA, Office of Air and Radiation, Office of Air Quality 

Planning and Standards, and Office of Mobile Sources, 

(EPA450/3-84-012C), July 1987. 

3. Draft Regulatory Impact Analysis, Proposed Refueling 

Emission Regulations for Gasoline - Fueled Vehicles — Volume 

II - Additional Analysis of Onboard Controls 

(EPA-450/3-87-001b), U.S. EPA, Office of Air and Radiation, 

Office of Air Quality Planning and Standards, and Office of 

Mobile Sources, July 1987. 

4. "PT Model Description and Users Guide," David B. 

Bartus, U.S. EPA, SDSB, August 10, 1988. 

5. "Effect of Running Losses and Excess Evaporative 

Emissions on Future VOC Emission Inventories," Memorandum from 

Richard Rykowski, EPA/OMS/ECTD/SDSB, to the Record, December 

22, 1988.