Even in full size cars the electronic systems (throttle, fuel injection and ignition) are usually mounted on the firewall, not the engine.  Fuel injectors can be considered servos.  And the throttle control is either a servo or an air controlled device that is effectivly a servo.  And yes, vibration is still a big issue as is temperature.

As Einstein said many, many years ago - if it ain't broke, don't fix it.  Well that's not precisely what he said but it sums it up.