Does anyone use these great toys? I have them both and they are unbelievably wicked fun. The GTech is more feature laden than the GTimer, but for acceleration runs the GTimer is easy to use as long as it is mounted in the center of the windshield and reasonably level. I originally used the GTimer in my S55 and recorded some blistering 0-60 runs along PCH at Crystal Cove (Newport Beach CA). a best of 4.40 and a whole bunch more between 4.42 and 4.63. I finally mounted it in the 575 and took one run in Phoenix, south on 56th St. between Cactus and Shea. It looks flat and is a mile between traffic lights, dead straight. A perfect road. In retrospect it may be a very slight downhill grade from N to S. Very early in the morning on Sunday. Not a soul around. Anyway my first run out the box was 3.97 - traction off, sport mode on shift at 7500 (F1). What a rush!