[sperry]

The older G-Tech has a single accelerometer. It uses the ignition pulses present on the power lead to determine RPM (count's all the sparks and divides by 4 for 4 cylinder motors).

The biggest reason it's inaccurate is due to the requirement of making sure it's absolutely level in the car, and that the car is traveling on absolutely level ground. You also need to enter the test weight of the car very accurately in order to get good results, since virtually every result is calculated.

Every time the car pitches, rolls, or yaws, and every little bump in the road, or up or down hill spot will result in loss of accuracy for the accelerometer, because it's an acceleration not caused by the force of the motor.

G-Techs are fun toys, but not very useful for real "testing". You can use them for back to back comparisons, but not for comparisons to other cars.

I believe the newer G-Techs have 3 accelerometers, so they can triangulate the acceleration force vectors and attempt to filter out latteral and verticle G's caused by poor instalation and roll and pitch. So it's probably a bit more accurate, however, I still wouldn't consider it more than a slightly cooler toy than the 1st.

Yes, I have one.