British-born investor and world record holder Charles Burnett III was among five people killed in a helicopter crash in New Mexico.
The group of friends, including a Zimbabwean opposition leader, were travelling to a ranch in the US state when their helicopter crashed in a remote area, according to the Associated Press.
Mr Burnett, 61, who was born in England but based in Houston, set a world record when he drove a steam-powered car at an average speed of 139.8mph in 2009.
He was in a long-term relationship with Andra Cobb, the only survivor of the crash and daughter of Paul Cobb, who was the co-pilot of the helicopter, AP reported.
New Mexico State Police said opposition leader Roy Bennett, Mr Bennett's wife, Heather; and pilot Jamie Coleman Dodd were also killed in the crash.
Police said on they received a call at 6pm local time on January 17 about a downed helicopter.
In a statement, they added: "Raton, New Mexico Police Department received a 911 call from a victim in the crash who reported the incident. The victim informed dispatch there were six people aboard the helicopter when it crashed."
They said a wreckage was spotted in a rancher's property east of Raton and was engulfed in fire.
The AP said Federal Aviation Administration records show the Huey UH-1 was registered to Sapphire Aviation LLC, which records show was linked to Mr Burnett.
The British-built steam supercar broke a 103-year-old world land speed record for steam-powered vehicles in the United States in 2009.
The 25ft-long British Steam Car - nicknamed the "fastest kettle in the world" - reached an average speed of 139.843mph on two runs over a measured mile at the Edwards Air Force Base in California.
The timing beat the previous record of 127mph set by American Fred Marriott in a Stanley steam car at the Daytona Beach Road Course in 1906.
Mr Marriott's timing was the longest-standing officially-recognised land speed record but it was beaten by the British team, based in Lymington, Hampshire, with Mr Burnett at the wheel.
An investigator with the National Transportation Safety Board was expected to arrive at the crash site on Thursday.
Police said Ms Cobb sustained serious injuries but was expected to survive.