What should you do when you're being chased by a car?

You probably aren’t pursuit trained by the police, so there is nothing to be gained by trying to out-run a stalker. 

The best thing to do is to concentrate on the road in front of you, and tell yourself that the car behind might not be following you after all and it might just be a coincidence (which is the most likely situation, and the safest way for you to act).