We drove our Toyota Scion a total of 16,737.6 miles between January 2 and December 31, 2009. That is the closest to "all of 2009" that I have from my compulsive gas mileage record-keeping.
Over that same period, we pumped 521.54 gallons of gas into that little car, at a cost of $1,169.32. We averaged 32.09 miles per gallon and it cost an average of seven cents a mile (not counting service costs, oil, wiper fluid and things like that).
Gas mileage in the car varied fairly widely during the year, from a low of 28.3 the last week of the year, when I was dealing with rain, snow, ice and general blech on the roads, to a high of 36.7 in the fall. That peak came on October 8, when I was driving back from Cleveland, Ohio -- a period of steady highway driving.