See also:

Parking brake
If you drive on wet roads or dirt-covered surfaces, road salt and/or dirt could get into the parking brake. In order to prevent corrosion and a reduction in the braking power of the parking brake ...

Vehicle data, GL 350 BlueTEC
The data stated here refers specifically to a vehicle with standard equipment. Consult an authorized Mercedes-Benz Center for the data for all vehicle variants and trim levels. ...

Cleaning the exterior lighting
  Clean the plastic lenses of the exterior lights with a wet sponge and a mild cleaning agent, e.g. Mercedes-Benz car shampoo or cleaning cloths. Only use cleaning agents or cleaning ...