Roger, Aurora had the Data race computer back in the early 80's that had a sound tower that you could attach to it. The controllers would cause the sound to go up & down. We did one race with them but it mostly sounded like a basement full of large bugs flying around! I guess that if you could somehow cycle it down several octaves and run it through some large bass bins & a sub woofer it would sound a lot better! . . . . . .and of course the revmatic bleachers too.
Then there was the Aurora Magna-Sonic cars with the sound box that sat on top of the gear plate.........
I have some old drum triggers that I've thought about putting around a various corners of my track & have them trigger assorted crash sounds when someone comes off & hits the wall!....each turn would have it's own crash sound so you would even know where you are crashing if you've lost sight of your car!........
I believe that David Smith, who built the computerized track years ago had a sound chip that was tied in to the controller movement........
This could turn into a great after market add-on product if developed right.
Tyco made some stuff too. I always liked the magnasonic boxes because they actually moved around the track. Everything else is stationary, which kinda takes away from the experience, to me. It would be cool to see some new stuff.
A guy I use to race with would video tape indy and nascar races, then throw the tapes in a small tv behind him on his workbench, just loud enough to hear in the backround, but not enough to be a bother to us talking. was actually really cool, try it.
Years ago I put a modified Pontiac Trans Am body on a SG+ chassis. I cut the hood to hang a blower out of it, so to make it sound like a real huffer I cut a flap in the heat shield under the motor and bent the flap to rub on the arm. It created a neat little whining sound (also like the card in the bike spokes trick). I got sick of it pretty quickly though.
If you wanted to get really fancy with actual F1 or stock car sounds there are digital options out there but it all depends on your budget.
Something to experiment with would be those digital voice recorder chips like you find in greeting cards. I'm sure there is some place that sells the chips and the ability to record your own sounds onto them. With a little tinkering you could set up triggers on the track using reeds or optical sensors that tripped different sound effects chips. The limitation would be minimal volume output.
A more expensive option would be a zone trigger software using a PC and web cams. Software like this can detect a moving object through a web cam and trigger WAV sounds, take pictures, take video and even activate other softwares. Really cool stuff!