Yeah, i can imagine that on some computers it could lag quite a bit with khas' awesome light effects! Sorry about that!
For the car, i had to choose between as you said, locking the direction or putting it how it is. I think in both cases its gonna look weird! ^^ if the direction were locked the car would suddenly jump down a case... Im gonna have a think about this, cause I'm wanting to use cars more in this project and in other ones i have in the pipeline!