@liudr: I am pretty much sure that you can open the door (at least partially) even at 160km/h (100mph). Here in Germany nobody assumes this to be very fast. This is just "fast". I find it always amusing when I see car chases in US movies when the needle of the speedometer trembles as it hits the mystic 100mph. When I am commuting at 160km/h I have to take care to avoid cars that are rapidly approaching from behind 
With regard to the anoying beeps: why does my car beep if the "passenger" (=my laptop bag) is not buckled up? At least it stops after some beeps. The previous one kept beeping for 5 Minutes before it gave up.