See also:

Weights
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Remove attached parts following use
Remove auxiliary mirrors, roof or rear luggage racks which are no longer required following use. Attached parts on the vehicle impair the aerodynamics and increase the fuel consumption. ...

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 ...