The electronic differential lock (EDL) permits smooth, comfortable starts on road surfaces that do not have a uniform coefficient of friction. If a wheel starts to spin, EDL brakes it as necessary so that power is transmitted to the wheel with the better traction. EDL reduces tire wear and works up to about 25 mph (
quattro®: up to about 50 mph). EDL is part of the
Electronic Stabilization Program (ESP) and the
traction control (ASR) .