Volkwagen wants US regulators to change a proposal to double auto fuel efficiency, arguing the plan puts it at a competitive disadvantage and penalises clean diesel engines.

The automaker did not put its name to an agreement backed by virtually every other major car company that underpinned an Obama administration proposal to boost efficiency targets to 54.5 miles per gallon by 2025.

VW said it remains hopeful changes will be made to reduce incentives in the plan that favour the biggest pickups - a staple of the Big Three US automakers.

The German carmaker also wants some benefit for the clean diesel engine in the new US-built Passat TDI which gets 43 mpg on the highway.

VW's US sales grew 40% in October to 28,000 units, the biggest gain for any manufacturer, and are running nearly 25% ahead for the year.

Jonathan Browning, chief executive of VW of America, said: “A lot of good work has been done, but there is room and a need for some improvements to keep a level playing field for all automakers to attain the challenging new goals."

Reuters reported that VW has met with transportation and environmental regulators as well as White House officials and said the company's principal concern is fairness.

Obama administration officials said they were open to hearing different views from car companies during the 60-day public comment period but stood by their decision to push incentives for petrol/electric hybrids and other electric vehicles.

President Obama wants 1m electric cars on US roads by 2015, a goal car companies say is overly ambitious considering that hybrids, which have been around for a decade, and newly arriving plug-in electric cars currently account for less than 3% of US sales.

Japanese manufacturers dominate the hybrid market while GM's Chevy Volt range extender is the most heavily promoted plug-in electric available in US showrooms.