Just a general reply here, but most high mpg cars have less to do with the car, than they do the driver.
Give a person a car that's usually getting 35 mpg, and the car will get 28 mpg because they will be using their instinct to rush around and keep up with traffic.
There is a list of 100+ driving techniques on this website which offer some good starter advice on how to improve your mpg through driving.
100+ hypermiling / ecodriving tips to increase gas mileage - EcoModder.com
Saving gas, is a state of mind more so than it is a feature of a vehicle.