Mine gives back to back consistent times which is what you want if you are using it for tuning purposes.It will never give the same times as at a track because the method of timing is different.The G-tech starts timing the instant the vehicle starts to move, at a track the timing starts when the tire clears the beam so you get a bit of a rolling start.Also the G-tech records the speed at the end of the 1/4 mile but at a track your speed is the average speed between two markers located before and after the 1/4.