Hmmm
I'm not sure if that would be beneficial to the majority of visitors, and here's why:
Most people don't own or use high-mileage vehicles and therefore such comparisons would not be applicable.
This site celebrates the high efficiency and success of hybrids, and comparing to vehicles that have high mileage, as well, but not lower mileage vehicles, would create an unfair bias against hybrids, making it seem as if they are not so stellar.
However, the GreenHybrid mileage database (
http://www.greenhybrid.com/compare/mileage/ ) accurately compares real data for a variety of cars, including non-hybrids (note the VW).