Troponin

I am not sure it's even a true accelerometer, but was wondering if anyone has tested out the 1/4 mile, 0-60, braking meters etc and put them to the test to see how accurate they are.

The biggest concern is, I have a buddy with a 2012 Challenger RT and his also has those timers. He is telling me his best time is a 4.8 or something like that, and his car is completely stock. For those that don't know, the Challenger RT is 370hp, and a fat pig, and the estimated 0-60, according to various sources, ranges from 5.5 to 5.9. He honestly believes his car is that fast now (but that's beside the point here). We know he's not actually going that fast.

So, anyone test and compare them with GPS or reputable accelerometers?