I am one of those guys that resets the odometer everytime I fill up. I know, Im weird. I usually get 42mpg when riding alone and "normal". If my girlfriend rides I always get 38mpg and I ride even more "normal" with her on the back. It is no big deal, I just thought 4mpg was a little much for a passenger. My girlfriend weighs 110 pounds too, just in case you all thought I was carrying a 400lb hippo on my bike. The only hippo is me at 225 lbs