I dont have one myself, but a guy on the E36 M3 board has one. He also drag races a good deal and has compared the Gtech times to the times he gets at the track. According to him they are spot on, with the only difference being the trap speed. The reason that is different is due to the way they measure your speed at a drag strip. Instead of measuring the actual speed they do an average of the 50 ft or so. So basically to answer your question, yes it is accurate. I plan on buying one myself one day