From last fall only slightly related to the original thread purpose:

With the larger tires the mpg reading is about 1 mpg off. So, 21 mpg. Not too shabby. I've never seen anything close to that since. I guess it was the perfect combination of weather - cool with a slight tailwind, traffic and speed.
The worst was a couple of months ago with 100 degree heat on the way to South Padre. The headwind was brutal and I was in a slight rush. 11.6 mpg.
Yikes.[This message has been edited by p_bubel (edited 10/14/2009 2:12p).]