I've had my IS300 for a year and a half now and I have never seen a problem related to drive by wire. There was the issue that was fixed with the ECU reflash, and the supposed hesitation with the 1 -2 shift, which some say is because the 2 is just an overdrive 1. Whatever the case, I just haven't seen any real problems with this type of thing. When I put the pedal down , the engine and trans give immediate and appropirate response at any speed.