GARDENA, Calif. --- Automotive hybrid systems expert David W. Hermance, Toyota's top North American engineer for advanced technology vehicles, died Nov. 25 while performing aerobatic maneuvers in his plane off the coast of San Pedro, Calif. A resident of Huntington Beach, Calif., he was 59. Hermance championed the virtues of hybrid technology before scientists, regulators, environmentalists, legislators and consumers. With a knack for explaining complex hybrid and advanced technology, Hermance served as Toyota's hybrid engineering ambassador in the U.S. "Dave Hermance was a gifted engineer and was highly respected by his peers in the automotive industry," said Yasuhiko Ichihashi, president of Toyota Technical Center, USA. "Dave's strong communication skills were instrumental in educating the public on Toyota's hybrid technology. He possessed unique skills which can not be replaced." Hermance's successful careers at General Motors and Toyota spanned four decades. Hermance spent the first 26 years of his automotive career with General Motors, where he led Durability Test Development and served in a variety of roles in the Vehicle Emissions Laboratory. In 1991, Hermance joined Toyota Technical Center U.S.A. in the Gardena, Calif., facility as senior manager in Engine Evaluation, with responsibility for evaluating North American passenger car engines. In 1992, Hermance was promoted to general manager of the Powertrain Department, where he was responsible for the development of engine and drivetrain calibrations for the North American market. He went on to become the executive engineer for Advanced Technology Vehicles and oversaw advanced technology communication for the North American market and regulatory activities in California. Up until his death, Hermance worked to promote hybrid and advanced technology vehicles in the U.S. Within the industry, he was widely recognized as an authoritative voice on hybrid power vehicles in the U.S. Hermance was instrumental in making hybrid technology appealing to mainstream consumers, in addition to environmentally aware car buyers. He was well-respected by industry analysts and environmentalists for his efforts to further advanced technology vehicles.