The speed sensitive feature you describe works in conjunction with a rain sensor feature.

There is a thumbwheel on the wiper stalk to adjust rain sensor sensitivity. Does that not work on your vehicle?

I don't know of a way to remove the rain sensor functionality.

All BMW models have the speed sensitivity feature. It also can not be disabled.

If the auto sensor isn't working properly, new wiper blades can help as they wipe the windshield more completely. Old blades leave a film, and the wipers never pause.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue