Most people outside the auto industry may never have heard of David Hermance.

Yet, Hermance, in charge of Advanced Technology Vehicles for Toyota, was regarded by some as the man responsible for bringing a more competitive version of Toyota’s hybrid-electric Prius car to the U.S.

More than that, he was the early point man for hybrid-electric vehicle technology in America, a well-respected, familiar face at auto industry conferences around the country, offering up a different view of automobiles of the future.

He had his work cut out for him, as the U.S. still was enjoying its love affair with big SUVs and pickups and the powerful engines that move them.

Hermance first joined Toyota’s U.S. unit in 1991 to evaluate the auto maker’s HEV engines for compliance with federal and California emissions regulations after having served 26 years as a General Motors engineer.

In 2000, he became the Japanese auto maker’s top North American engineer for the HEV system used in the Prius and other hybrid models.

Under his guidance, Toyota deployed a more powerful and more fuel-efficient powertrain for the second-generation Prius that arrived in the U.S. in 2003. Earlier models had not sold well, but sales of the new North American version grew to more than 100,000 units in 2005.

Hermance was special in other ways. He was an engineer who was able to explain in plain English complex hybrid technology to the media and most other audiences. He also drew respect for his non-combative manner in addressing criticism of HEVs’ failure to deliver projected fuel-economy gains.

So the news came as quite a shock that Hermance, 59, had died Nov. 25 when the aerobatic plane he was piloting crashed into the Pacific Ocean off the coast of California, where he reportedly often flew to practice maneuvers such as loops, spirals and stalls.

Some might consider stunt flying a far cry from Hermance’s staid occupation of powertrain engineering. But they would be wrong.

Such flying requires a certain mastery of complex mathematics, along with the ability to problem solve under extreme conditions. Best of all, it brings instant satisfaction, as well as an element of risk.

A pilot friend, who also works in the auto industry, tells me it’s no mystery that those drawn to automobiles often are drawn to aircraft.

“Going fast is going fast; precise maneuvering can be even more fun in three dimensions, and determining where the edges of the envelope are can be equally challenging and rewarding in both arenas,” he says.

Hermance worked hard and played hard at the things he liked best. In doing so, he excelled at both. His death is a tragedy by any measure. But his enormous influence on the auto industry will live on.