A CHP investigation concluded that Mr. Smith, 67, "was making a U turn" and was at fault in the May 25 accident, CHP Officer Eric Parsons said. The accident occurred along Sand Hill Road between Whiskey Hill Road and the Interstate 280 interchange.
The car's driver, Woodside resident Anthony L. Rose, 87, is not being charged.
Mr. Smith, a former chief executive officer and president of San Jose-based Altera Corp., was wearing a bicycle helmet, CHP Officer Grace Castillo said.
He and his wife had donated $1 million to the town of Portola Valley's open space fund. They were also active in efforts to rid the town's roads of litter.
The cause of death was multiple traumatic injuries, according to the San Mateo County Coroner's Office. Mr. Rose was not injured.
The damage to Mr. Rose's green Volvo indicated a substantial impact.
Damages to the car included a broken right headlight lens, a large basketball-sized dent in the right front quarter panel, a "large" hole in the passenger side windshield, and a dent in the roof above that hole, the CHP said. The car was towed from the scene.
The hood had black scuff marks, possibly made by the handlebars on Mr. Smith's bicycle. Damages to the bike included a detached front wheel and a broken front fork, the CHP said.
Mr. Smith was found 46 feet and his bike 74 feet from the point at which the vehicle came to rest, the CHP said.
In a May 30 story on the accident, the Almanac reported that the Smiths had given $1 million to the town's open space fund in an effort to clean up litter in town. Local residents who are familiar with the donation say the donation was not tied to the Smiths' interest in ridding the town of roadside litter.
The Almanac was unable to reach Ms. Smith for comment.