A system, device, and corresponding method for enabling a user to accurately control, monitor, and evaluate performance of a vehicle. A portable programmable computer device that a user can readily install by plugging it into a diagnostic connector port of the vehicle. The system includes a detector for detecting the start time of first movement of the vehicle independent of the on board diagnostic system. Velocity data from the onboard diagnostic system is time stamped by a clock in the device and stored. Velocity curves are generated from the velocity data and time stamps. Wheel spin is accounted for by smoothing the velocity curve to determine a point of inflection in the velocity indicative of termination of wheel spin and creating correcting velocity and acceleration curves by solving equations from the inflection point backwards on the curve down to time zero. From the corrected curves, an accurate distance is calculated.