I feel weird resonding to a 1.7 year old post, but I don't have access to old physic materials, and I can't host a grand prix on a slippery surface. Buuuuut....
Assets > Create > Physic Material

@WNP78

@WNP78 @KingHandspider Basically, I want a car I made to handle like its on asphalt.

@WNP78 But what if I was making, say, a race track? (in other words, a modeled terrain mesh?)

Also make sure your terrain is set to the "terrain" layer (top of the Inspector window) and in the terrain options (cog tab) Material is set to Built in Legacy Diffuse

There used to be a physics material included with the mod tools, I don't know where it went. I still have it from an old project, and the properties are:

Dynamic Friction: 1
Static Friction: 0.75
Bounciness: 0.05
Friction Combine: Average
Bounce Combine: Average

@Chancey21 thx

@WNP78
@Gestour
@Mushr0om

@HellFireKoder

@AndrewGarrison