Any way to script car or compile it that way so it slows down on specific surfaces?

Hey, is there any way to compile or any $keyvalues commands that would make rigged car slow down or drift on specific surface? I compiled car and made it work, tested on my F1 track map and to be honest I think players will take shortcuts on it driving over gravel since it has no impact on speed.
Here is what I mean basically:

I don’t think that would be a keyvalue, I think that is something you should setup in the map.

Oh damn. Ok thanks anyway.