Mercedes-Benz 2000 C-Class Operator's Manual page 105

Caution !
Vehicles with Acceleration Slip Regulation (ASR)
If the vehicle is towed with the front axle raised, the engine must be shut off (electronic key in steering lock position
0 or 1). Otherwise, the ASR will immediately be engaged and will apply the rear wheel brakes.
Caution !
Vehicles with Electronic Stability System (ESP)
If the vehicle is towed with the front axle raised, the engine must be shut off (electronic key in steering lock position
0 or 1). Otherwise, the ESP will immediately be engaged and will apply the rear wheel brakes.