Principle
The Auto Start/Stop function helps save fuel.
The system switches off the engine during a stop, for instance in traffic jam or at traffic lights.
Drive-ready state remains switched on. The engine starts automatically for driving off.
General information
After each engine start using the Start/Stop button, the Auto Start/Stop function is ready. The function is activated from speeds of approx. 3 mph/5 km/h.
Depending on the selected driving mode, the system is automatically activated or deactivated.
Engine stop
Functional requirements
Steptronic transmission
The engine is switched off automatically during a stop under the following conditions:
Manual engine stop
If the engine was not switched off automatically when the vehicle stopped, the engine can be switched off manually:
When all functional preconditions are fulfilled, the engine switches off.
Air conditioning system when the engine is switched off
The air flow from the air conditioning system is reduced when the engine is switched off.
Displays in the instrument cluster
General information
The display in the instrument cluster indicates that the Auto Start/Stop function is ready for an automatic engine start.
The display indicates that the conditions for an automatic engine stop have not been met.
Total time with switched-off engine
ECO PRO driving mode: depending on the vehicle equipment, the total time that the engine has been switched off using the Auto Start/Stop function is displayed on an automatic engine stop.
The total time can be reset via the trip data.
Functional limitations
The engine is not switched off automatically in the following situations:
Starting the engine
Functional requirements
Steptronic transmission
The engine starts automatically under the following preconditions:
Driving off
After the engine starts, accelerate as usual.
Safety mode
After the engine switches off automatically, it will not start again automatically if any one of the following conditions are met:
Some indicator lights light up for a varied length of time.
The engine can only be started via the Start/Stop button.
System limits
Even if driving off was not intended, the deactivated engine starts up automatically in the following situations:
Without Mild-Hybrid technology: additional functions Auto Start/Stop
Depending on the vehicle equipment and country- specific version, the vehicle features a variety of sensors for assessing the traffic situation. The Auto Start/Stop function uses this information to adapt to various traffic situations in a proactive manner.
For instance, this applies to the following situations:
A message appears on the Control Display, depending on the situation.
The function may be restricted if the navigation data is invalid, outdated or not available, for example.
Activating/deactivating the system manually
Principle
The engine is not automatically switched off.
The engine is started during an automatic engine stop.
Without Mild-Hybrid technology: via button
Press the button.
Via selector lever position or Driving Dynamics Control
The Auto Start/Stop function is also deactivated in selector lever position M/S or in SPORT driving mode of the Driving Dynamics Control.
Without Mild-Hybrid technology: display
Switching off the vehicle during an automatic engine stop
General information
During an automatic engine stop, the vehicle can be switched off permanently, for instance when leaving it.
Steptronic transmission
1. Press the Start/Stop button.
2. Set the parking brake.
Automatic deactivation
General information
In certain situations, the Auto Start/Stop function is deactivated automatically for safety reasons, for instance if no driver is detected.
Malfunction
The Auto Start/Stop function no longer switches off the engine automatically. A Check Control message is displayed. It is possible to continue driving. Have the system checked by a dealer's service center or another qualified service center or repair shop.