Peakster has a mp$ calculator on his signature, maybe it'd be a good idea to add this to the stats image most of us attach to our signature. Use the method of average fuel cost/ per mile of fillup + additional averages per fillup.
I actually like $/mi better. I think it's easier to understand. I get 9.5 cents per mile, which seems more comprehendable than getting 10.5 miles per dollar. I would be a neat thing to have on the images though, since some people my get worse mileage but have cheaper gas.
this is why I would like to see a collum for non fuel costs in the gas log, I keep all of those in my note book, and a few times a year figure out how much it costs me to drive per mile, my last figure was around 21.9 cents per mile if I counted the car as a compleat loss today.