Except that we are. The DSC light was changed, and on newer models the DSC light has the logo "4x4" added underneath it. God only knows why.

Everything Drex (and a few others...) said about the DSC light was right

So, back to the original question. It really isn't a 4x4 light. Bozo, you always have 4x4. (It does say 4x4, which shows that BMW has bowed to the lowest common denominator among their owners.)

Leave the switch alone, and take advantage of the features of DSC in snow and ice. The only time to turn it off is when you are stuck in deep snow, and when you try to accelerate a wheel slips; in those caes the DSC reduces the throttle. You literally can't drive out. In those cases, turn off DSC and you can spin the wheels to try and get unstuck. Also works well on steep driveways at low speed. BMW also recommends turning it off when you have chains on, or in sand.

Edit: Hey Breyton, you can type faster than me...

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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