However vehicle physics is a nice addition to the engine, I find it quite useless without a terrain type/material picking. It'd be great to know, what kind of surface is under the wheel, so for example, it'd be possible to modify slip or traction values.
AFAIK, right now knowledge about terrain type under certain point is unsupported.

I would love to see this feature too as it has other uses. For example, you could adjust the speed of a character or unit based on the type of material it is moving across. i.e. it walks slower on mud than on grass.

This would be very useful. I can think of ways to fake it but none of them are as elegant as native support.

EvilNoodle

I'll try to add this soon

Such a feature would be also very useful to change character's step sound depending on what it's walking.