best cars
I have found that the best cars you can use are trucks. They are easy to hold on to from almost anywhere (except for maybe the front). Any car will work though and I recommend using a car that is not to high up cause you don't want to be floating when you put your arm in the window. I also recommend a car with a smaller engine as they are easier to handle at low revs. There are a few pictures below of the cars I have, or do, use to tray surf.
Trucks are good!
Pickups are better!
Remember any car will work if you can figure out the greatest way to do it.