Hello, I ask the question here in the tyre forum, because I am especially concerned with rolling resistance. By rolling out attempts in the plane you can determine the rolling resistance with a car, and the resistance coefficient cw*A. I would like to do that, only my speedometer, especially for the measurement at low speed is not exactly enough, and I had to find out that my Navi indicates the speed too much time delay. Now I am looking for a way, for the experiments Could you read out the ABS sensors? Has anyone experimented with a bicycle speedometer on the car? Could you borrow exact GPS equipment somewhere? Or does someone else know anything else? Thank you, Frieder