That would be awesome, thanks!
Lots of people on the smart car forum I hang out on use
http://www.spritmonitor.de to track their fuel economy, and it has a little forum signature thing that its member can use, but I like Fuelly better (it's much more visually appealing and easier to navigate) so it would be great if we had something similar.
A blog badge would also be nifty! +1 votes for both!