How does friction work?

[jes]

I see that the vehicle wheels have "friction slip" set to 9 and 10.5. This doesn't make much sense to me as a coefficient of friction, so I can't really work out what these values mean?

I also couldn't work out where the coefficient of friction of the road surface is configured, it seems like I must be missing something.

Great work on the vehicle-demo btw, it is very useful!

Cheers.