Alltho I must admit it would be bloody awesome, I think we rather need a completely new car for that purpose. I am dreaming for a rallycross pack, filled with some more rallycross tracks, aswell as 2-3 car class of rallycross + that crosscar thingy.
Below you'll see some picture of what a crosscar is. Basically it's similar to MRT, just made for dirt tracks and such. It could work with just adding hybrid/knoble tyres on the MRT, but preferable a whole new car would be better for this area.
I think this could prove GREAT fun to the rallycross parts of the game. With some more tracks I think more people would join the fun in rallycross within LFS. These cars have an extreme accleration, but not too fast top speed, purely made for small tracks, autocross fun!