It's amazing what speed and conditions will do for your MPG.
Last week and the week before I took a 10-day vacation, in which I drove up to Seattle, WA (from Reno, NV).
Because my alternator will still out in the Benz I took a 1997 Toyota Corolla. This car typically gets 28-32 MPG in town.
As an experiment (a long, semi-boring, but then relaxing and rewarding experiment) I decided I would drive no faster than about 57-58 mph the whole way (with the exception being downhill stretches where I didn't have to use the gas at all). I would stop and add gas to full level about every 175 miles.
The best MPG achieved on the trip was 56, on about a 300 mile stretch through Eastern Oregon. The average MPG ended up being about 50.
Frankly I was shocked to see these numbers (with my usual around-town-going-70mph mpg being about 30). But I think it does show that great MPG can be achieved if we are willing to just SLOW DOWN (and if we're driving on a no-stop-lights freeway
)