Interesting stuff:
I just entered in the Focus to the system here, and went looking for data such as the drag, frontal area, mileage, etc. According to this website:
http://www.fueleconomy.gov/Feg/noframes/20703.shtml
The economy (city/highway/combined) is listed as:
22/32/26
Whereas I'm absolutely certain the window-sticker said 30/36 for city/highway when I bought it... I hate how numbers like these seem to change willy nilly, and apparently are just made up by the manufacturer to suit their needs. Anyway, it makes me feel better about my 29.5 MPG average I suppose.
Also interestingly, I looked up the aero info on my last car that annoyingly got the same mileage as the Focus, and it has a Cd of only .3 and a frontal area of only 19.3. It was a lot shorter, sleeker car.