Once upon a time when I bought my wife's hybrid, I asked around about the advertised 47 mpg. The sales guy said he was actually achieving 366 mpg in his, but he plugged it in morning and night and never took it on the freeway. 8 months after buying he was still on his first tank of gas. It's all in how you manipulate the conditions. He told me that MPG ratings listed on vehicles are achieved under the most strict and stringent conditions. Everything is perfect on test day, right down to the barometric pressure, humidity level, temperature, wind speed, vehicle speed, elevation change (there is none) That is how the manufacturers achieve the numbers that the average consumer never will. I have over 100K on my hybrid in 3 years. I have been on 2k mile trips where I have gotten as high as the advertised 47, and as low as 38. I have had a few 35 mile trips home that I averaged 62, and the same trip that has been as low as 36. I even had one 12 mile trip, mostly down hill in elevation, that I got 79.6 mpg. Headwind, season, idiot drivers, daytime, night time, it all plays into mileage. Your best average should be taken over a longer period of time and mileage, a few months and several thousand miles, to give you your true average. My best calculations on the hybrid over thousands of miles is 39.6. Ford adjusted their sticker average down to 42 about 6 months after I bought the car and gave me an $800 'I'm Sorry" check. If I take it easy and drive like an old man, I can keep the running average up around 44, but that's no fun! The 7.4L Burb is another story. No matter what I do, fully loaded or completely empty, towing or not, I can't get any better than 14, and usually no worse than 12. It's the nature of the beast, and I love it!