See also:

Head airbags
In a lateral impact, the head airbag supports the head. ...

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

Aerodynamic optimisation of underside panelling
As the excellent drag coefficient (cd = 0.26) would suggest, the aerodynamics of the new BMW 3-Series have been intensively honed in a state-of-the-art wind tunnel. The optimised aerodynamics also ...