Mercedes Seeks EPA Mileage Credit for Stop-Start System

Daimler AG is asking the U.S. Environmental Protection Agency for credit for the engine stop-start technology and other fuel-saving measures incorporated into its Mercedes-Benz vehicles, Automotive News reports.

Daimler estimates that its vehicles spend 24% of their time idling. The stop-start system switches off the engine under those conditions, but the resulting fuel savings are don't show up on the EPA's standard test cycle. Daimler is petitioning the EPA to consider crediting it for "off cycle" fuel economy gains.

In the past, the company simply paid fines for failing to meet fuel economy mandates fines totaling $349 million for model years 1985 to 2011, according to AN. But the new standards don't allow companies to pay fines as an option to compliance.

If the EPA rules in Mercedes' favor, the agency would give Mercedes cars a 5% boost in fuel economy, or about 1 mpg, AN says. The company also is asking for credit for energy-efficient lighting and tinted windows and ventilated seats that reduce the need for air conditioning. The EPA agrees that such features save fuel.

Daimler's passenger cars had a corporate average fuel economy of 30.2 mpg in model year 2013, short of its target of 33.1 mpg, according to the National Highway Traffic Safety Administration.

Environmental groups oppose Daimler's petition, noting that the Mercedes stop-start system can be turned off with a button.