It's true there are no end-to-end 100% drive-by-wire cars. But there are certain drive-by-wire systems in many modern cars. Electronic throttle control[1] is widespread (or universal?) and brake-by-wire[2] is already used by Mercedes and Toyota.

1. http://en.wikipedia.org/wiki/Electronic_throttle_control 2. http://en.wikipedia.org/wiki/Brake-by-wire