My wifes full size Taurus wagon with a V6 gets 30MPG on the interstate.
Some of it can be done but in order to get that kind of jump in efficiency something has to suffer. Size or mileage...both is a pipe dream.
Meet the 2010 Ford Fusion Hybrid, a mid-size car that gets 8 mpg better fuel economy than a "Smart" car.
There is hope then and the goal set doesn't seem so far off now, does it?