I use Panasonic cameras GS-400 and GS-65 becasue I had them before I started doing a lot of in-car video. They have done a great job for 5 years now even surviving 4 hour enduro races.
But if I was starting fresh I would get the Go-Pro or something similar.
This is a mount that I made for in-car stuff when there is no roll bar. Some square tube, a couple U-bolts and a tripod head I had laying around.
Many racing orgainizations will not permit the use of suction cup mounts (even the chasecam which is very good). I have had this suction cup setup on a car up to 85MPH with no problem. The large one is 6" and the smaller ones are 3" and they have built-in pumps to draw a vacuum.
I used this setup and the in-car one along with a third camera on a tripod up on a hill beside the course to make some Auto-X videos for a friend. When I am just fooling around I use the large suction cup, the rod and mount on the inside of my windshield to get nice clear "going down the road scenery" videos.