This is what I used at the last autocross. With some industrial double sided tape you can mount it virtually ANYWHERE.
http://replayxd.com/
It's small, light-weight, and easy to use. A suction cup mount would come in handy for glass surfaces, but that's not the problem we're facing. You can mount the scotch-lock that comes with the package horizontally on the parcel shelf behind the seat, and mount the camera and rotate it to face the front.