Without thinking about it too long, I can think of three people I've known in my life who died in a car.
Jerry"
Perhaps that's because Pilots are more memorable people than ordinary drivers?

Just as an aside,...I wonder how much our perception is influenced by the occasion of death vs the actual number of people we know who've died? For example, because we are all so interested in airplanes...perhaps an airplane death is more prominent in our memory than a death from a more common cause.
Further example: Someone I've "known of" is different from someone I've "known". Since student pilot days, I've recalled a guy named "Rocko" who I saw occasionally at the coffee pot in the FBO where I was learning. He was PIC of an Aero Commander one night IFR in clear air over the Grand Canyon when a marine F-4 Phantom mistook his position lights for that of an aerial refueling tanker. The Phantom flew up his tailcone and killed him, while the Marine bailed out successfully. If anyone had asked me if I knew Rocko, I would have said yes, and I would have counted him in this recent discussion thread. I really never recall any direct conversation betwixt us, but I count him as someone I knew who died in a plane.
I also recall seeing my first auto-fatality. I was 6 or 7 years old riding with my Mom near St. Augustine, Tx and she tried to keep me from looking at the driver of a wreck on the wayside whose head was stuck through the steering wheel and lying lifeless on the dash. I only just remembered the occasion as I thought of this discussion thread. I'd never claim to know that person, nor would I normally have ever thought of the event if I were asked about my knowledge of deaths. I've seen probably 10 or 20 such auto-deaths over the years but don't have them stored in my priority memory-recall because they aren't associated with a personal reason for doing so....as driving deaths are not integral to a hobby or life's profession or passion... like flying is. They also weren't talked about at the local auto repair center or sevice station that I also don't spend several hours each weekend at catching up on whatever gossip is being tossed about there.
And that's the problem with anecdotal surveys, and conclusions about wide-ranging topics based upon personal recollection and experience. It simply isn't a valid research method.