I am new to the GreenHybrid website. Just bought 2008 Ford Escape Hybrid. Have noticed quite a few FEH's listed with mileages averaging quite a bit higher than the listed sticker mileage of 34 mpg. I am having trouble maintaining 31 mpg while driving in the green zone (very conservatively). I was wondering what factors affect city mileage estimates that don't involve a driver's driving habits. Some of these might be operating temperatures, fuel octane or producer quality, terrain, etc. Or are these errors in estimating mpg.