I know it sounds absurd, but it really is like this. Typical car ECUs have about 40-50 MHz processors and there are about 70 ECUs in a modern car. Imagine switc

I know it sounds absurd, but it really is like this. Typical car ECUs have about 40-50 MHz processors and there are about 70 ECUs in a modern car. Imagine switching them all to 1GHz ARM cores - how much more expensive it will be and how much more space you will need. You will also most probably need bigger PCBs and cooling and there comes the additional weight. Also the CAN protocol may be crappy for development, but allows for more simple hardware design (connectors, wires etc), which again saves weight. The cables in a modern car weigh about 50 kg so imagine doubling that in order to use a better protocol - this would be like always driving with one more passenger. Such things may look small, but they quickly add up...