Coolant

See also:

Safety
Both the coupe and convertible have front airbags plus side-impact airbags built into the front seats. As required of all 2012 models sold in the U.S., the 640i has standard antilock brakes and an ...

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

Coolant temperature
Should the coolant, and with it the engine, become too hot, a Check Control message is displayed. Check the coolant level. ...