Jason,

I think most of us now know that driving habits, trip length, and ambient temperature make up most of the differences seen in MPG.

Since trip length and ambient temperature are part of the information you collect, I think it would be interesting and useful to collate our aggregate data with these points in mind, and see it graphically.

Perhaps you could have two controls -- maybe sliders -- that let one pick a temperature range and trip length, giving bar graphs of the data subset for each car. The sliders need not be continuous; discreet groupings would work well, and would allow non-real time processing of the data.

I very much agree with your comments above, except to say that MPG is *very* much a contest. Just not against others, but a personal adventure :-)