WARREN, Mich. — General Motors will keep making big trucks and SUVs because U.S. buyers demand them, but a major portion of them will be gas-electric hybrids in the near future, retiring Vice Chairman Bob Lutz said.

Lutz didn't give details, but said GM must apply hybrid technology to more vehicles in order to meet fuel-economy standards that will rise 40 percent to an average of 35 miles per gallon by 2020. The cost will likely be spread across GM's lineup, since charging individual buyers for a hybrid system would make vehicles too expensive. GM has seven hybrids in its lineup now.

The hybrid revolution is one of many changes Lutz has witnessed in his 47-year career at all three Detroit automakers and BMW AG. That career will end May 1, when the 78-year-old will retire after revamping GM's lineup to critical acclaim.

"I really have achieved what I set out to do," Lutz told The Associated Press in his office at the GM Tech Center.

He leaves with some regrets. He's wistful about Saturn and Pontiac, two brands he overhauled that GM has decided to shed. Saturn had a world-class lineup before its demise, but GM didn't have the money to market it properly, he said. Pontiac was in the midst of a comeback and was a big seller with young buyers. A miniature Pontiac Solstice sports car sits under glass in his private conference room.

But Lutz supports the decision to dump the brands, leaving GM to concentrate on Chevrolet, Cadillac, Buick and GMC.

"It's like the B17 bombers in World War II. As they were limping back to the base in England, they threw a lot of valuable stuff overboard to lighten the airplane," he said.

He also leaves triumphant. At the Tech Center, a sprawling, 1950s-era campus that is testament to GM's former might, Lutz plotted GM's future, including his proudest achievement: The plug-in electric Chevrolet Volt. The Volt, due out later this year, can go 40 miles on an electrical charge and is also part of GM's strategy to make more fuel-efficient cars. Lutz said the automaker is also planning a separate line of all-electric vehicles that won't have backup gas engines like the Volt does.

He plans to write a book about the last eight years he spent at GM, where he watched as the automaker sank into bankruptcy protection last June and got a federal bailout, sparking the restructuring that ultimately led to his retirement.

Lutz concedes that one reason for his departure is his diminished role at the automaker. He originally planned to retire at the end of 2009, but stayed on after ex-CEO Fritz Henderson asked him to lead GM's marketing efforts.

When Henderson was ousted from the company in December, his successor, Ed Whitacre, took away Lutz's marketing duties and made him a "special adviser," an ambiguous position that left no one reporting to him.