I can't understand why one would turn it off. It is on when you start the car, it doesn't hurt anything, it doesn't cost you fuel mileage, and if you have to make a sudden extreme evasive maneuver it can come in very handy as it will work to stabilize the vehicle, helping you maintain control. That applies to both wet roads and dry.

If you are on slick streets and it is intervening on acceleration due to a lack of traction, it is really telling you that you are driving with too heavy a right foot for the conditions.

If you want to push the button and turn it off (ie the DSC light is on, telling you it is inactive) I would only do that on snow-covered streets, when the vehicle is not moving and you can't get moving due to the lack of traction. Turning it off raises the thresholds for traction control intervention, and lets you spin the tires to try and get moving. Once you are moving, push the button again to turn the light off, which turns it back on. If the roads are that slippery, why wouldn't you want active stability control?

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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