The best way of doing this is as follows:

At the start of your program rotate your car by increments of say 10 degrees (Or as much or little as you want) and store each rotated frame in your imagelist or an array or wherever. Then, when it comes to the main game loop, all you have to do is blit the appropriate image to the surface which is fast. From what I gather from your post you are redoing the rotation at every frame, it's no wonder it's very slow. Hope this helps.