i recently watched a video on the beamng youtube channel and it said they aim to include police chases and demolition derby? wouldn't this only work if cars can break down? just an idea that after a certain amount of damage near the engine could cause the cars to break down. I know after a while the drive shaft can stop but if you press q a few times the car works again (dont know if thats a bug that will be patched in the future).
The game, while awesome, is still in very early alpha. There are tons of things planned. The game probably won't be finished until late 2014 or 2015. There are TONS of things planned. I have a few demo derby videos on my channel. I highly recommend that you get the game now because it's really awesome and it'll probably get more expensive in the future.
The only current possible way to break a car from getting power is to break the driveshaft. There is probably going to be overheating due to a damaged radiator, oil leaks and the likes in the future