Manufacturing Companies
- General Motors
- Daimler Chrysler
- Toyota
- Ford Motor Company
- Cummins
- Caterpillar
- Detroit Diesel Corporation
- Mack
- International
- Briggs and Stratton
- Consumers Energy Company
- Lyondell Chemical Company
Trade Associations
- Alliance of Automobile Manufacturers
- Association of International Automobile Manufacturers
- Engine Manufacturers Association
- American Petroleum Institute
- Western States Petroleum Association
- Outdoor Power Equipment Institute
- American Coal Council
- Canadian Vehicle Manufacturers Association
- Renewable Fuels Association
Governments
- Environmental Protection Agency
- Southeast Michigan Council of Governments
- State of Colorado
- State of California
- State of Michigan
- Environment Canada
Other
- Annapolis Center
- American Enterprise Institute
- Coordinating Research Council
- Kirkland and Ellis
- Moore and VanAllen