2005 Mercedes SL-Class Owner's Manual - Page 215

Controls in detail Driving systems Cruise control lever The Distronic system is operated by means of the cruise control lever. The cruise control lever is the uppermost lever found on the left-hand side of the steering column. Activating Distronic You can activate Distronic if you are driving between 25 mph (40 km/h) and 110 mph (180 km/h) the ESP is activated ( page 82) When Distronic is activated the speedometer display will show a message such as DTR 60 mph. If Distronic is deactivated, the speedometer display will show the message DTR --- mph. In the following cases you cannot activate Distronic: 1 Set current or higher speed 2 Set current or lower speed 3 Deactivate Distronic 4 Resume at last set speed up to two minutes after starting the engine when you brake if you have set the parking brake if the gear selector lever is in position P, R, or N. if the ESP is switched off 1 Set speed 2 White DTR indicator lamp E i The vehicle speed displayed on the speedometer can briefly vary from the speed setting on the distronic system. 213