Here's the latest video for
which has ace rally driver Ken Block talking about how dirt on different surfaces impacts the traction of the vehicle and how you have to compensate or it. It's an interesting video and there's plenty of nice gameplay footage mixed in so it doesn't get too stale.
If you want to know why Ken Block was picked to take over for the late, great Colin McRae then you should check out
this video from Top Gear which shows Mr. Block giving James May a quick once around the track. Hopefully that's in the game as well.