Time out here, we need some clarification.
PANatsFan said his Mazda gets 27, and his Mustang 31 highway. He didn't say anything about EPA estimated mileage standards for those cars. So PA, do your cars get the mileage you reported, or are you merely quoting EPA standards without empirical evidence of your own?
Those are the averages, the EPA standards.
My first tank, my 5 got a little under 19 per gallon, but that was definitely mostly "city" driving, the standard is 21 city, and it's brand spanking new.
I'm getting over 20 at this point, and this time it will be "highway"-like. I understand the standards, but I also understand that your car needs to perform legally within spec now - minimum for my 5 is 17mpg.
I assume they are road tests and not lab tests, but I also assume they have pro drivers who know just how to drive the car and maximize the performance. However, I also assume that all manufacturers use the same tricks to try and get the best score possible, so they should have equal advantages.
The new Chevy Malibu gets 31mpg, but I'm willing to assume the 5 is possible heavier and less efficient than a sedan. The Mustang intrigues me. Probable a google search of "mustang gas mileage" or a quick check at Edmunds will answer my questions. The combined rating of my 5 is 23mpg, best in class for all "minivans" is 24mpg, but I'm very skeptical that a full-sized minivan could beat the little 5.