We have problems with their smaller cousins. These stand about a meter tall wikipedia says they can travel at about 30mph which sounds close. They can jump out of the bushes and be in front of your car in less than a second. Bounding away then 180 degree jump back in front of you. And in plague numbers. You have to get a special permit to hunt them, and have a gun license also (heavily restricted).
After dark, drive with high beams as much as possible and be more wary of the edges of the road than oncoming traffic.
Hitting one will smash the plastic bumper on you car and likely will do more damage. Having said that I have seen a 60foot trailer thrown about 50cm in the air after putting a wheel over a wombat.