Yes I have had it at the track several times and it is accurate. I have not had time to fool with the dyno features though, there are like 6 cops for every person where I live so they are up your @ss everywhere you go and I haven't found anywhere to test it without getting pulled over.

Here is a test run I made on my old car:

dynoc.jpg

and the fact on a "real dyno" I ran a 285.8whp/255wtq the gtech is right on. It is about 8% off and the weight is about 8% too heavy so if you subtract that it would have been amazingly close.

Typically the drag mode will show 5mph faster than your actual trap speed in a 1/4 mile so if you subtract that out you should be right on.