In planning to take the 20 hour, 1250 mile round trip to Cincinnati in a few weeks, I'd love to know how to maximize fuel economy. The estimated gas cost of $90 - $120 (and burning 35 to 50 gallons of gas in 3 days) slightly haunts me.

I found some interesting links on what hurts MPG and being more efficient. But I've heard that every car has a single optimal RPM at which they get the maximum fuel efficiancy. Of course, your gear dictates speed which alters wind resistance which alters efficiency, but let's assume 5th gear; cruising gear.

Is there a way to calculate or otherwise determine that optimal RPM and/or optimal speed? Can I determine any other conditions needed to help (ie: drive slower up a hill to avoid overworking the engine?)?

Hm, that fueleconomy.gov site is pretty cool, especially the find a car feature. Haha, "cars that don't need gasoline" is interesting. No hydrogen powered cars on there. Someday, hopefully.