LOS ANGELES (Nov. 27) - A pilot who died when his aerobatic plane plunged into the sea was an engineer who promoted fuel-efficient hybrid vehicles and was dubbed the "American father of the Prius."

David Hermance, 59, didn't invent the gasoline-electric engine but the Toyota Motor Corp. executive made it palatable to a skeptical U.S. public, colleagues said Sunday.

"When that car came out, no one knew what it was," said Bill Reinert, a Toyota national manager. "Dave dedicated his life to championing this technology."

"He was the American father of the Prius," he said.

Hermance, a Huntington Beach resident and father of two grown children, also was a dedicated pilot. Authorities believe he was the only person aboard his single-engine Interavia E-3 when it crashed Saturday afternoon off Los Angeles.

Witnesses said they saw the plane - a two-seat Russian aerobatic model that can be built from a kit - performing loops and dives before it plunged straight down.

A search team found the wreckage in 60 feet of water Sunday morning, county Fire Capt. Mark Savage said. Hermance's body was found floating on the surface.

Hermance was executive engineer for Advanced Technology Vehicles at Toyota's technical center in Gardena, company spokesman Mike Michels said.

He joined Toyota in 1991 as a senior manager, then became a general manager in the company's powertrain department. Before that, he was with General Motors for a quarter-century, working on vehicle emissions and durability test development.

Toyota developed the hybrid engine in Japan but it didn't do well when it was introduced into the United States in 2000. Hermance helped develop a newer model, released two years ago, that had greater acceleration and was more fuel-efficient.

He also promoted the hybrid concept to lawmakers and others.

"He made the Prius something that worked for the American market," Roland Hwang, vehicles policy director for the Natural Resources Defense Council, told the Los Angeles Times. "When people think of hybrid systems, they think of Toyota, and that is due in good part to Dave's work."