I'm constantly seeing, what I believe, are outrageous mileage figures released by car manufacturers. Example, Mazda claims the Mazda 3 gets 58 mpg, but if you check them out on this site, no one comes close. Does anyone know how these figures are arrived at? I drive a 2011 Smart, mostly on the highway, and average 5.1 litres per 100 km, under 50 mpg.
All depends what you drive, where you drive, when you drive but most importantly, how you drive. In the MPG marathon in the UK last year, the winner was a Ford Fiesta that got 108 MPG. Most people in that model probably only get 60 to 70 MPG, but the government figures suggest it will do 88 MPG.
Always take government figures with a pinch of salt. I like to think of them as "targets"but moat people just look at them and laugh. In all fairness, since I changed my driving style, I get close to 40 MPG for my car, the government figures claimed it will do 42 average so im not far off.
In addition to those points, keep in mind that you're looking at data for differently equipped models (likely different engines) in different places where a "gallon" can be a different size. Mazda USA says up to 40MPG highway for the 3. Some people report 40+.