So an iPhone on the dash I tap to start the timer on isn't accurate???That is a nice setup. I've seen people post YouTube videos of their 0-60 mph and use a stop-watch as a timer - always they are way, way off. I've counted the video frames (usually YouTube is 30 fps, but each video shows the rate in the 'info') and commented on the video w/ the actual 0-60 mph time.
And then there was the very first 0-100 kph video from a guy in Japan that reported 9.2 - turned out he had traction control enabled and it was a rainy day...