Flat hwy at between 45-65mph commuting 40 miles Hwy 101 bay area, more go than stop, I get 44-48mpg. On return home on rolling hills on Hwy 280, same speeds, I get 40-42mpg. On streets during weekends, normal driving, I get 38-40mpg. At speeds above 75mph, I'll only get 40mpg (huge difference) and have gotten under 33mpg by going 90mph. My driving style is normal to light footed on my HCH, not like some of the Hybrid idiots that drive 15mph in 35 zone and 55mph in 65 zone. Those slow morons are really hurting the environment because all the other drivers waste a huge amount of gas getting around. But they do get 60mpg or whatever. In my V8 400hp other car, my mileage only fluxates between 20.5 and 21.0 mpg if going from 65mph to 90mph so huge difference in HCH if going faster or rolling hills.