Have you guys seen my racing vids? I always use in-car vids - sometimes on the rear deck and sometimes on my helmet.
I use two different mounts from ChaseCam.com - a c-clamp for the latch on the rear deck and suction cup mount that can be used on the outside of the car or inside on the windows. I also have a little kit I got off Ebay that has a bullet cam and a helmet mount for the bullet cam as well as an external microphone. It all hooks up to the red/white/blue A/V wires for my main video camera.