Q: In my Volvo S80, there is a W button by the stick shift. I have no idea what it does, could someone help me out?
A: it's for (W)inter driving. when it's sleeting or snowing and the conditions are slick, push that button and the power applied to accelerator is moderated so you don't spin-out. Try it sometime, and when you start from a stop you'll feel the car is slowly applying the power. Almost like it starts in 2nd gear.