I just learned this and thought it may be news to you, too.

'Bill Hickman was already an established stuntman by the time The Wild One was being filmed and his expertise on motorcycles landed him work on the Stanley Kramer production. At some point during the project, Hickman was injured and was unable to continue. It is never clear whether he was hurt while filming a stunt for the movie, although one account (by the late Clyde Earl) had him taking a spill in a motorcycle race not connected with the film. However, Hickman is clearly shown in several of the publicity stills from The Wild One.

Hickman spent some of these earlier days as driver and friend to James Dean, driving Dean's Ford station wagon towing Dean's famed 550 Spyder nicknamed "Little [censored]", and often helping and advising him with his driving technique. He was driving the Ford station wagon and trailer following Dean on the day of Dean's fatal accident and was the first person on the scene.

Hickman was an extra in Dean's 1951 feature movie debut, Fixed Bayonets!. A rare personal quote from Bill on his friendship with Dean: "In those final days, racing was what he cared about most. I had been teaching him things like how to put a car in a four-wheel drift, but he had plenty of skill of his own. If he had lived he might have become a champion driver. We had a running joke, I'd call him Little [censored] and he'd call me Big [censored]. I never stop thinking of those memories."

In another interview with James Dean expert Warren Beath, Hickman is quoted as saying, "We were about two or three minutes behind him. I pulled him out of the car, and he was in my arms when he died, his head fell over. I heard the air coming out of his lungs the last time. Didn’t sleep for five or six nights after that, just the sound of the air coming out of his lungs."

While Hickman had many small acting (mainly driving) parts throughout the 1950s and 1960s, he worked primarily as a stuntman. He sustained a couple of significant injuries during this time, including breaking several ribs in a bad trick-fall in the film How to Stuff a Wild Bikini (1965). However, it was the car chase alongside Steve McQueen in the 1968 film Bullitt for which he is usually remembered. Hickman was to do all his own driving; portraying one of two hit men, he drove an all black 1968 Dodge Charger 440 Magnum R/T through the streets of San Francisco, using the hills as jumps.

In a professional driver's touch (before compulsory restraints were introduced in California), Hickman's character buckles his seat belt before flooring it at the beginning of the pursuit by the Highland Green 1968 Ford Mustang 390 GT, driven by Steve McQueen.

The dangers were real: in one shot Hickman accidentally loses control and clips the camera fixed to a parked car. '

There's more. The link is worth the read.

https://en.wikipedia.org/wiki/Bill_Hickman#References

Hickman had quite a life. Pretty much balls-out: read about how the French Connection chase developed...
Some time back - maybe a year or so - there was a discussion here where the gas station photo of Lil [censored] & the Ford wagon was posted.
I first saw that photo decades ago and my gut feeling was that those 2 cars were related; subsequently confirmed
There's another photo of both cars in L.A. that looks like it may be at the origin of that fateful trip.

Did he die?

William Hickman (January 25, 1921 – February 24, 1986)

https://en.wikipedia.org/wiki/Bill_Hickman