Carmageddon: Max Damage

You can check your progress towards this, in the Criminal Record tab.

This is done during the fox missions you get halfway through the game. As the fox, you are the highlighted car and mustn't let anyone touch you. When you are a highlighted car the timer starts around 2-3 minutes and counts down. If someone touches you they become the "fox/highlighted car". Simply touch them to become the fox again. You must be driving for the counter to work. Since the AI are such bad drivers just drive to a tower or something that has a lot of turns and drive in short circles. When the counter hits 0, you win. If you play landing pads, use a kangaroo powerup to jump on top of the middle section after it falls down. To make it fall down you first have to have a fast car to drive under and out of it before it crushes you or you could drive under it, hit respawn, wait for it to drop and then kangaroo on top. The enemies don't seem to be able to get up there they end up going underneath and dying repeatedly. Cleanup In Freeplay as career only gives you about 20 minutes roughly.