How many computers on a car?

Answer 1

I used to work for SIEMENS VDO Automotive, a car electronic manufacturer. In 2003, the most "computerized" car in Germany was the BMW 7 series, the top model had 99 computers/microcontroller. The least equiped was Opel Corsa, just 7 computers. In case you are not familiar, microcontroler=1 chip computer.

The fastest coputer and the most powerful is the one controlling the powertrain (engine+transmission), but for different functions like ESP, this can be assigned to several computers. ABS = a separate computer. Safety (=airbag and others) is a dedicated computer, can be combined with a separate one which measures the weight on the passenger's seat and decides if there is someone and if this is a child. There is at least one computer for the dashboard. One in each power window-lifter, one in each electrically controlled mirror, another one for the sunroof. Rear lights may have their own computer, sometimes one for each side. All these computers report to a central unit, other than the one responsible for the power train. Another computer if the car has headlights washers. Another one if you have the back door of an SUV/Minivan power assisted. Don't forget the windshield wipers.

Why so many ? Believe it or not, it is cheaper. Sometimes just by replacing a big high-current switch with a computer controlled by a tiny switch (like the ones on your PC keyboard) the price is reduced. Plus, the software of the car is developed long before the mechanics of the car. If any mistake occurs, or if the specification is changed, just change the software, it takes few days of reprogramming. And it is much more reliable.