Distributed by Mettoy in the UK, Computacar was a programmable toy car. In the US they were known as the Amaze-A-Matic by Hasbro. The steering and motor direction were controlled using external punch cards which slowly progressed through the control system.
It took some practise before you got experienced enough to program the car to drive between a bunch of traffic cones as per the explanation on the box.
You had to feed a strip of card into the front. The card had notches cut into it, depending on the notches the toy car would steer left/right, and go forward or backward. There were precut cards but you could also design your own.
The AMAZE-A-MATICS toy was a finely designed, very fun toy which was comprised of the following items: One of four futuristic cars, pre-programmed cards, blank cards for your own programs, racing pylons, instruction booklet.
These program cards really did mechanically program your car to execute manuevers. Each car had two spring-retained levers that rode on both edges of the cards. One controlled steering, the other controlled the gearbox on the car. Depending on the depth of the cuts on the cards, the car's steering and forward/neutral/reverse status were changed. The car pulled these cards through its undercarriage via a roller system, and the car's control levers followed the edges of the cards.
The six pre-programmed cards came with each set, and their layouts were contained in the instruction booklet. You could also cut your own cards following instructions on each card very simply. As a kid, I remember making one that made the car go backwards in a circle the whole way!
When you knew how to program well, you could set your pylons up and have the car easily drive right around them and miss them completely. The car was pretty accurate, and if you were not abusive to it, would last a long time.
What's it worth? Take a look at this Computacar price guide: sold listings for a value indication.