I'm one of those people that keeps a close eye on my vehicles' average gas consumption rates. According to my fuel logbooks, my wife's SUV has gotten around 20.2 MPG over the last two-plus years; my sedan has gotten 24.7.
This past week, the DC area was visited by a fast-falling snowstorm that hit right around rush-hour (and, "rush-hour", in the DC area, is normally a four hour window in the morning and evening). When I go to my regular office, it's about a 19-mile commute. When traffic's sane, it's about a 35-minute trip. Wednesday, that same trip took me over 5.5 hours to complete. Normally, I get about 22MPG on that 19-mile trip when taking my wife's SUV to/from work. In addition to the five-hour snow-penalty, there was a serious MPG penalty: I got around 11.2MPG from the tank. Given that I'd already made the 22MPG morning run to get to the office, it means I probably got rather less than 11.2MPG on the trip home.
Argh. I hate driving in the DC-area during bad weather.