could be used for reducing fuel consumption with a foresighted driving style. Even in this case, the rev
counter in the instrument cluster displays zero engine speed (0 engine revolutions).
Brake energy regeneration (Recuperation/charge)
When the vehicle brakes, the electrical energy is generated by the electric motor, which works as an
alternator and charges the high-voltage battery. The same thing occurs while the vehicle is coasting to
a stop or driving downhill.
Energy regeneration is shown in the instrument cluster display or on the Infotainment System screen.
The combustion engine may be switched off automatically in this situation. The instrument cluster
tachometer will show zero engine speed (zero engine revolutions).
Automatic starting - combustion engine
The combustion engine is started automatically in a number of situations.
x Engine temperature is too low.
x Catalytic converter temperature is too low.
x High-voltage battery being charged at high rate when decelerating. The high-voltage battery
cannot absorb any more energy and for this reason the electric motor cannot brake the vehicle. The
combustion engine comes on to help slow the vehicle down (engine brake).
x Engine hood is open.
x Leaving the vehicle when the electric motor is still “live”. The status of the electric motor is not
always obvious, particularly when the combustion engine is not running. The combustion engine will
therefore start if the driver's safety belt is unlatched or the driver's door is opened when the
transmission is in Park (P) or Neutral (N) .
Energy flow display
Fig. 253 Energy flow display (Variant 1). Left: Instrument cluster. Right: Infotainment System.
Fig. 254 Energy flow display (Variant 2). Left: Instrument cluster. Right: Infotainment System.
.WARNING
High voltage systems in the engine compartment can cause electrical shocks or even
electrocution, severe burns, other serious injuries, and even death!
x Never short-circuit the electrical system. Be especially CAReful when using jumper
cables. The vehicle's battery could explode!
x To reduce the risk of electrical shock and personal injury while the engine is running or
being started:
– Never touch ignition cables. Never touch other components of the high-voltage
electronic ignition system.
– Never touch the wiring of the HID - High Intensity Discharge (Xenon) headlights.
.WARNING
Moving parts in the engine compartment can cause serious personal injury on contact.
x Never reach into the area around or touch the radiator fan. Contact with the blades can
cause serious personal injury. Always remember that the radiator fan is temperature-
controlled and can come on suddenly even when the engine has been switched off for a while
and the key has been removed from the ignition.
x If you have to perform a check or repair when the engine is running, there are more risks
from the rotating parts, such as the drive belts, alternator, radiator fan, etc., and from the
high-voltage ignition system. Always use extreme CARe.
– Always make sure that jewelry, loose clothing and long hair do not get caught in
rotating engine parts. Before starting any work remove your jewelry, take off your necktie,
tie back and cover your hair, and do not wear clothing that can hang down and get caught
in moving engine parts.
– Always use extreme caution if the accelerator pedal has to be depressed to perform a
check. The vehicle will start to move even if the parking brake is on.
x Never leave any objects in the engine compartment, for example cleaning rags and tools.
Objects left behind can cause malfunctions, engine damage, and even fires.
.WARNING
Operating fluids and some materials in the engine compartment can catch fire easily, causing
burns and other serious personal injuries!
x Do not smoke.
x Never work next to open flames or sparks.
x Never pour or spill operating fluids or other flammable liquids on the engine. These fluids
can ignite on hot engine parts and cause injuries.
x If work on the fuel system or the electrical system is necessary:
– Always disconnect the 12 Volt vehicle battery. Make sure the vehicle is unlocked when
you disconnect the battery, or the alarm will go off. Never touch the electrical wiring of the
ignition system.
– Never work near heaters, water heaters, or other open flames.
x Always have a functional, approved fire extinguisher nearby.
