DEARBORN, Mich. - Ford Motor Co. will meet the tougher federal fuel-economy regulations Congress wants to impose by 2020 without having to abandon any of its lower-mileage truck or sport-utility vehicle lines, chief executive officer Alan Mulally promised yesterday.

"Our commitment is to improve the fuel efficiency of all the vehicles no matter what the size," Mulally said after signing a four-year contract with the United Auto Workers.

The auto industry's fleet of new cars, SUVs, pickup trucks and vans will have to average 35 miles per gallon by 2020, according to the agreement that congressional negotiators announced late Friday. That compares with the 2008 requirement of 27.5-m.p.g. average for cars and 22.5 m.p.g. for light trucks. It would be the first increase ordered by Congress in three decades.

Democrats plan to include the requirement in broader energy legislation to be debated in the context of $90-per-barrel oil, $3-plus pump prices, and growing concerns about climate change. The House plans to begin debate this week.

Environmentalists have sought stricter gas-mileage standards for years, saying that is the most effective way to curb greenhouse-gas emissions and oil consumption.

The energy bill will help accelerate plans by automakers to bring more fuel-efficient technologies to conventional engines and alternatives such as gas-electric hybrids and vehicles running on ethanol blends. For the first time, for example, manufacturers will receive credits for building vehicles running on biodiesel fuel.

Ford's executive chairman, Bill Ford, said yesterday that it would be a stretch to meet the 35-m.p.g. standard, but he was confident Ford could do it.

"We have to do it," he said, "and we have the best people in the industry getting ready to do it."

Ford shares fell 22 cents to $7.29 in afternoon trading Monday. Genberal Motors Corp. shares fell $1.17 to $28.66.