I used this one http://www.b-hague.co.uk/hague_car_suction_mount_sm1.htm mounted to the rear window and didnt have any problems. The only modifcation I had to do was remove the rear view mirror. Just make sure your video camera has a remote control so you can start/stop. Here are a couple of vids
I use the same b-hague. Very stable and still going strong after 4 years of use. Makes you look a n=bit Top Gear though as its very obvious if on the windscreen
I use the GoPro Hero HD with the tube mount on the front grille below the kidneys for the ultra low forward view, and a suction cup mount on the passenger wind deflector panel behind the passenger headrest for my ContourHD for interior view of the car and track.