avg miles per...
 

"Avg miles/tank" and "Avg price/tank" -- it looks like these are really "Avg miles/fuel-up" and "Avg price/fuel-up" calculations?

Not that it wouldn't be great to have actual calculations per tank, since that would probably make for fairer comparisons between people with the same car but different fueling habits. Maybe if Fuelly knew (or I could tell it) how many gallons can fit in my car's tank?

Yep, we're using "tank" in a very casual way right now and I see how that could be misleading. We're using it in a "I just filled up my tank" way, not as an exact measurement of gallons a tank will hold. We'll either make that more clear on the site or we'll switch to using Avg miles/fuel-up. It's not as a friendly as tank, but more accurate. Thanks.

I think Average Days between a fillup would be cool to see, too.