The auto industry and its allies in Congress are lobbying congressional leaders and the Bush administration to back fuel efficiency increases that would maintain separate standards for passenger cars and trucks.

The industry opposes a plan that was approved in the Senate last June that would increase fuel economy standards on new vehicles to 35 miles per gallon by 2020. In 2008, cars must average 27.5 mpg and trucks need to reach 22.5 mpg.

Auto executives have been making their case to the Bush administration about the energy bill and a regulatory plan on vehicle emissions being developed by the Environmental Protection Agency and the Transportation Department.

The industry, along with agriculture and recreational groups, back an alternative led by Reps. Baron Hill, D-Ind., and Lee Terry, R-Neb., that would seek a combined standard of 32 to 35 mpg by 2022 along with separate standards for cars and Trucks.

Environmental groups say the proposal does not go far enough to reduce oil consumption and want the final energy bill to include fuel economy standards passed by the Senate.

“Any energy bill that has the Senate fuel economy compromise in it guarantees oil savings,” the Sierra Club’s Ann Mesnikoff said Friday. “The Hill-Terry bill is a weaker goal.”

General Motors Co. Chairman and Chief Executive Rick Wagoner on Tuesday met with Al Hubbard, director of the National Economic Council, Nicole Nason, the administrator of the National Highway Traffic Safety Administration and EPA officials to discuss energy issues.

Ford President and CEO Alan Mulally is expected to be in Washington next week to discuss the energy bill and fuel economy regulations.

“It’s quite clear that there are a variety of efforts both legislative and administrative that are under way and could potentially come to a close this year,” said GM spokesman Greg Martin. “So it’s important that we clearly state what our positions are and our concerns on the details.”

In a letter to White House chief of staff Josh Bolten on Friday, Hill and Terry and 62 other lawmakers urged the Bush administration to support their alternative.

They said their approach was more realistic and would “protect good-paying American manufacturing jobs, preserve consumer choice in auto vehicles and set achievable timetables for compliance.”

In a separate letter, 13 Senate Democrats, led by Sherrod Brown of Ohio and Byron Dorgan of North Dakota, urged Majority Leader Harry Reid, D-Nev., to ensure that the energy bill includes job protections for small car production.

The Senate measure would eliminate the so-called “two-fleet rule,” which keeps different mileage standards for cars and trucks and end the different calculations used for vehicles made overseas and in North America. The United Auto Workers union has said eliminating the separation would lead to a loss of 17,000 jobs involved in small car production in the United States.

“We believe that these policies should be aimed at promoting - and ultimately expanding - manufacturing jobs in the United States,” the senators wrote. It was signed by Democratic presidential hopefuls Hillary Rodham Clinton of New York, Barack Obama of Illinois, Chris Dodd of Connecticut and Joe Biden of Delaware.

A group of senators, including Michigan Democrats Carl Levin and Debbie Stabenow, wrote congressional leaders earlier this week in support of the alternative.