He was an engineering wizard for Toyota with an environmentalist's heart -- an executive who championed hybrid gasoline-electric cars years before global warming entered the popular conversation.
He translated the virtues of the fuel-efficient Prius in appearances before lawmakers and scientists, promoting a car of the future that would win the embrace of a once-skeptical American public.
David Hermance, 59, of Huntington Beach, who died Saturday afternoon when his experimental plane crashed into the ocean off San Pedro, was remembered fondly for his efforts to advance the kind of technology that could one day reduce America's reliance on fossil fuels and ease pollution caused by the nation's love affair with gas guzzlers.
"He was the American father of the Prius," said Bill Reinert, his longtime colleague.
As executive engineer for advanced technology vehicles at Toyota's technical center in Gardena, Hermance played a key role in adapting Japanese technology for consumers in the United States.
The first generation of the Prius, which runs on a combination of a gasoline engine and an electric motor, received a lukewarm reception when it arrived in the United States in 2000 after its debut three years earlier in Japan.
Hermance was instrumental in helping to develop a second-generation vehicle, released in 2004, to appeal to the American public, with greater acceleration, better fuel efficiency and lower emissions.
"Dave repeatedly demonstrated his commitment not just to Toyota's profits but to the planet," said Jason Mark, vehicles director at the Union of Concerned Scientists in Berkeley. "He garnered the deepest respect from the engineering community and the policy community. His family should be tremendously proud of the contribution he made."
Hermance was Toyota's hybrid engineering ambassador to the United States. He appeared before regulators and legislators, translating the complex and sometimes arcane idiom of hybrid technology into plain English that made it seem not only plausible but appealing, environmentalists said.
"He made the Prius something that worked for the American market," said Roland Hwang, vehicles policy director for the Natural Resources Defense Council.
"When people think of hybrid systems, they think of Toyota, and that is due in good part to Dave's work. He was Mr. Hybrid, the American face of the hybrid."
