I recently devised this riddle, please enjoy:
A thief is driving a stolen vehicle, feeling very nervous. In his mirror, he notices a car, very close behind him. He switches lanes, but instead of passing him, the car follows him. He pulls over and slows down, giving the car the chance to go by, but it too slows down and remains solidly in his rear view, even following him off the road.
Annoyed, he guns it, lurching back onto the highway -- but the other car stays perfectly in sync, matching his every move, weaving in and out of traffic with reckless abandon.
Night begins to fall, and the thief notices that his nemesis doesn't turn on their headlights.
Finally, he takes a ramp and makes a few quick turns. When he sees that he can't shake the pursuer, he becomes so frustrated that he pulls over again, gets out, and approaches the vehicle, which, of course, had come to a stop behind him.
Only then does he realize that the car behind him has no driver.
What's the explanation?
(No remote controls or robotics are involved, and no spiritual activity occurred, possession etc. He did not hallucinate, the car was real).
Answer: