Statement in Response to Notice of Proposed Rulemaking On Reforms to the Testing, Calculation, and Labeling Procedures For Motor Vehicle Fuel Economy Issued by the Environmental Protection Agency

Docket Number EPA-HQ-OAR-2005-0169

Submitted by

Union of Concerned Scientists
Natural Resources Defense Council
Public Citizen

April 3, 2006

We would like to commend the Environmental Protection Agency (EPA) for its decision to reform the testing and calculation procedures used to determine fuel economy ratings for cars and light trucks. Consumers, policymakers, and nongovernmental organizations alike rely on the EPA’s numbers as an objective measure of vehicle fuel economy, but these numbers have been coming under increasing fire for their failure to reflect the performance realized by drivers in the real world. The EPA has correctly recognized that this is a serious issue and that its procedures are in dire need of revision. 

We are writing today to emphasize our shared view that the EPA should initiate, in cooperation with the auto industry, a comprehensive study of real world driving patterns and in-use fuel economy. The Agency should strive to ensure that it has at its disposal the most reliable and up to date information possible. These data would be invaluable both for bolstering and refining the proposed 5-cycle methodology and for developing new test cycles. New test cycles that accurately reflect current driving patterns represent the most reliable means of generating fuel economy information. By testing vehicles under the same conditions in which they are likely to be used, the need for vehicle-specific adjustment factors can be eliminated. At the same time, the tests will fairly reflect the potential fuel savings of various existing and emerging technologies, something which may be missing from the proposed 5-cycle methodology.

A study of in-use driving patterns and fuel economy would involve collecting data on fuel consumption, speed on a second-by-second basis, trip start and end times, and air conditioner and defroster usage. In addition, it would be invaluable to collect data on ambient and engine temperatures, additional auxiliaries usage, and other factors relevant to fuel economy. Vehicles would be drawn from a representative range of climates, urban and rural environments, and driver demographics, and preferably would include vehicles using a variety of technologies, such as hybrids, diesels, and conventional vehicles with fuel-saving technologies (e.g., cylinder deactivation, continuously variable transmissions, etc.). Finally, the study would be conducted over a sufficiently long period to account for seasonal variations in environmental conditions and driving patterns.

We urge the EPA to develop a plan for leading an in-use study of driving patterns and fuel economy, and to use the data gathered in such a study both to improve on its 5-cycle methodology in the future and to develop new, more representative test cycles.

Union of Concerned Scientists
Natural Resources Defense Council
Public Citizen