First off, I would like to mention that when I was playing on your purchased game, and i noticed when I did some off-roading and then I noticed the tires were squealing on dirt, it was making the same noise as when it peels on the pavement. and second off, the traction transition between dirt and pavement is exactly the same as pavement. For example, I put one of the tires on pavement then the other on dirt to see if one side would spin, and the side with the pavment was the side that slipped. If you could fix these few flaws, that would make your game just that much better and realistic. P.S. Last time I checked when I drive under the water my vehicle floods for some reason (when you go underwater in the game you can still drive.)
In my opinion there is more important stuff to do in Alpha then make your car flood when you go underwater, As for the dirt/pavement situation, I've never really payed attention to any differences, Maybe ill go see what you mean