See also:

Close the windows and glasssunroof
Driving with the glass sunroof and windows open results in increased air resistance and raises fuel consumption. ...

Remove attached parts following use
Remove unneeded auxiliary mirrors, roof or rear luggage racks after use. Attached parts on the vehicle impair the aerodynamics and increase the fuel consumption. ...

Wiper blades
1.  Fold out the wiper arm and hold it. 2.  Press together the locking spring, arrows 1, and fold out the wiper blade, arrow 2. 3.  Take the wiper blade out of the catch mechanism ...