With the correct tires for the conditions, there is no need for AWD plain and simple.
Just took my 535i RWD 6spd out in the snow with Pirelli Pzero Sotto snow tires and it faired just fine with the 10 inches we have on the ground. It did just as good as my AWD 335i with Blizzaks. The AWD is just dead weight added to the car IMO
2013 Alpine White F10 535i. JB4 S2, Quad Tip Magnaflow Exhaust, H&R Springs
2011 335ix Le Mans Blue w/ M Sport SOLD
2003 Turbo Cobra 765rwhp/650rwtq 9.77@126 pump gas, lifting @ the 1000ft mark