Five others, including the pilot and his passenger, were injured in the crash on a stretch of Interstate 15 that has been the scene of several emergency landings.
Witnesses said the single-engine plane appeared to be having problems before it banked and came down, California highway patrol officer Chris Parent said. One man said he did not hear the plane’s engine as it passed overhead.
The Lancair IV landed on its belly and skidded about 75m before striking the rear of a black Nissan Altima that was stopped at the side of the road in San Diego County near Fallbrook.
The driver of the car had pulled over to synchronise the Bluetooth device on his phone, Mr Parent said.
The impact crumpled the back of the car, fatally crushing Antoinette Isbelle, 38, of San Diego in the back seat and injuring three others in the vehicle.
“The plane went completely into the trunk and pushed the rear bumper almost into the rear passenger seat,” said John Buchanan, spokesman for the North County Fire Protection District.
Pilot Dennis Hogge, 62, and his female passenger suffered major injuries, Mr Parent said. The driver suffered moderate injuries, and his other two passengers were expected to survive their injuries.
The plane was once owned by baseball player Matt Nokes, who made a noteworthy landing on busy I-15 when the engine failed on its second flight in February 2000.
Nokes guided the high-performance plane to a smooth landing and safely taxied off the road without injuries.
He went on to fly the plane every day for five years without incident before selling it. He said it had been rebuilt several times since he sold it.
“It was crazy,” Nokes said. “Everything worked out so beautifully. It was almost a humorous thing. Unfortunately, it doesn’t always turn out that way.”
When Nokes heard about the crash, he unsuccessfully tried to reach Mr Hogge, but did not realise he had been injured. He described Mr Hogge as a good man, an outstanding pilot and a master plane builder.
“It’s just horrible to hear about,” said Nokes, who spent 11 years with baseball teams including the Detroit Tigers and New York Yankees.
The Federal Aviation Administration and National Transportation Safety Board will investigate the crash.