Step 1.: Install GPS transmitter in the car.
Step 2.: Make a paper note and put in in your cars window.
"I have are very particular set of skills; skills I have acquired over a very long career. Skills that make me a nightmare for people like you. If you let my car go now, that'll be the end of it. I will not look for you, I will not pursue you. But if you don't, I will look for you, I will find you, and I will kill you."
Now make him suffer.