First on-board computers in cars
While it’s tricky to define “computer,” one could argue that the Bosch D Jetronic first used in Type 3 Volkswagens is 1968 was a computer. The system was primitive by today’s standards, but it sensed manifold pressure and engine temperature. It used trigger points in the distributor to turn on the injectors, and the computer determined when to shut them off.
Engine Control Units (ECU) came onto the scene in the mid-1970s. For instance, the sub compact 1975 Chevy Cosworth Vega's ECU was an analog computer that sat in a box behind the dashboard. It was made up of hundreds of diodes that controlled fuel injection.
By the 1980s, in-car computers not only controlled fuel mixture and timing, they controlled most of the electronic processes — climate control, braking, and the odometer.
By the beginning of this century, of course, the on-board computer became one of the most important systems in the vehicle, controlling navigation, advanced climate control, communications, and entertainment devices.
Shown above is an old OBD2 car computer