Toy racing cars
The idea is to outfit your common everyday Hotwheels cars with technology allowing them to follow paths drawn by you. You could make them speed up, slow down or whatever, using special annotation. Also, you would not need a special surface at all. In other words, you could create The Perfect Track right on your living room floor.
Not sure how real any of this is, and how much of it is just conceptual mumbo jumbo, but you?re free to follow these next links to decide for yourself. The Line riders page. The two designer? Finally, the story came VIA WMMNA.
Better, clearer page with pictures of actual cars and stuff right here. It?s beginning to look like these things have actually been made, though obviously not in production yet. And check this link also.