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U.S. Department 

of Transportation

Research and

Innovative Technology

Administration

Volpe National Transportation Systems Center

July 25, 2011

MEMORANDUM

SUBJECT: Ex parte meeting with 

FROM: Maurice Hicks, NHTSA

TO: Docket No. NHTSAThis memorandum documents a meeting held on 

regarding the proposed fuel efficiency and greenhouse gas standards for medium

vehicles and engines for model years 2014

EXA: Stephen Remondi, Doug Hatfield, and Alex Alajbegovic

EPA: Byron Bunker, Cle Jackson, Arvon Mitcham, Chien Sze, Cheryl Bynum, Rich Zhang, Sam Waltzer, and 

Angela Cullen 

NHTSA/DOT: Angel Jackson and Maurice Hicks

The following topics were discussed during the meeting:

Background

EXA requested a meeting with EPA and NHTSA to discuss testing approaches for determining the 

aerodynamics drag coefficient for heavy duty tractors.

EXA stated that CFD has significant benefits over wind

not being limited to a 0 degree headwind (Zero Yaw), non

closed source environment. EXA has validated CFD mo

laboratories used by industry. During the meeting EXA and the agencies discussed 

EXA’s models and CFD modeling.

EXA asked the agencies to: 

a) Re-run GEM model results for baselines used by EPA

b) Consider best practices for aerodynamic simulation considering all the tools currently available 

in the market. 

Volpe National Transportation Systems Center

eeting with EXA Corporation

, NHTSA

-2010-0079

This memorandum documents a meeting held on November 30, 2010 between EXA, EPA

regarding the proposed fuel efficiency and greenhouse gas standards for medium- and heavy

vehicles and engines for model years 2014-2018. The attendees included:

Stephen Remondi, Doug Hatfield, and Alex Alajbegovic

Byron Bunker, Cle Jackson, Arvon Mitcham, Chien Sze, Cheryl Bynum, Rich Zhang, Sam Waltzer, and 

Maurice Hicks

The following topics were discussed during the meeting:

EXA requested a meeting with EPA and NHTSA to discuss testing approaches for determining the 

coefficient for heavy duty tractors. 

CFD has significant benefits over wind-tunnel testing. Modeling has superior benefits by 

not being limited to a 0 degree headwind (Zero Yaw), non-moving wheels (or road conditions) and a 

closed source environment. EXA has validated CFD models to several full scale wind tunnels test 

During the meeting EXA and the agencies discussed the availability of 

run GEM model results for baselines used by EPA with CFD results for aerodynamic inputs.

best practices for aerodynamic simulation considering all the tools currently available 

55 Broadway

Cambridge, MA 02142

, EPA, and DOT 

and heavy-duty 

Byron Bunker, Cle Jackson, Arvon Mitcham, Chien Sze, Cheryl Bynum, Rich Zhang, Sam Waltzer, and 

EXA requested a meeting with EPA and NHTSA to discuss testing approaches for determining the 

tunnel testing. Modeling has superior benefits by 

moving wheels (or road conditions) and a 

dels to several full scale wind tunnels test 

the availability of 

with CFD results for aerodynamic inputs.

best practices for aerodynamic simulation considering all the tools currently available 
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c) Consider best practices or approaches to moving models to public domain for validation of 

model results by industry.

The agencies agreed to consider the above requests.