Not often on the track from what I have seen but on the road it can be especially at dusk when they come out. Seen a fair few damaged trucks at work and a friends dads car from one. Wombats are also bad news as they are so heavy, it is supposed to be like hitting a 20-30kg boulder in the road.

Tip with Kangaroos, you are not supposed to brake if you about to hit one as it dips the nose of the car which in turn scoops the kangaroo up and can result in it coming through the windscreen. In the panic, the kangaroo kicks and in rare occasions has been known to kick the driver to death (not heard of that happening for quite a while though fortunately).