h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

There are, if memory serves, three TV movies made from the Knight Rider series.

Confusingly, two have the same name: Knight Rider 2000.

The first one (KR2000) is where KITT gets his super pursuit mode. In the second, Michael is retired and the car is gone. There are hilarious scenes with Michael fitting KITT into his Chevy.

There's also one where KITT becomes a hardtop convertable.

There is also a pretty good game out on PC and Playstation 2, although the PC game is better. IT features KARR, Gareth Knight (looks like Michael, illegitimate son of head of Knight Foundation and FLAG.) and Gareth's toy, Golliath, the mollecular bonded juggernaut. Very good plotline. Involves a plot to mass produce the mollecular bonded shell that KITT and KARR have.

Also in the late 1990s there was a series called Team Knight Rider (TKR) which was 5 people and five vehicles. A sports car, a 4x4, two motorcycles (that merge into one) and another car. Very very bad show, worked on the premis that each car has a flaw, as no-one should have an indistructable vehicle. Also they moved around in a 747 that could land vertically.