Which is why there are hundreds of road signs, on rotating poles, which read "4WD with chains required" -- rotated into view as conditions worsen and well before roads close. But I suppose you don't drive in the mountains during those kind of conditions (as you think the Whistler road is tough). The pacific storms are not to be under-estimated, and whistler gets an incredible amount of snow bordering on glaciation, but the road is very easy for those conditions. Of course chains are required -- that is a given -- but minivans are normally OK to Whistler. My own preference would be for a 4Runner though.