I like the idea of MPG cruise.
Don't forget the tranny may shift down. For autos that may save gas as the engine revs go up he throttle can go down. Look to keep the engine in the fat part of the torque curve for most engine torque with lowest RPM.
My motor home (Check my garage below.) is my attempt at "hyper Mileing" Any time the tranny shifts down the engine speeds up and the MPG drops like a rock! It has a 454 Chevy engine and the big cubic inches need fuel to satisfy the 14.8 to 1 fuel ratio. I like coasting, 999 mpg.
I usually get instant MPG about 12, but that becomes tank 8.5 mpg average, allowing for acceleration up through the gears. Each time it shifts up I get better mileage.
I am using an MPGuino as a fuel monitor.
Total fuel mileage is usually 10.5 mpg from calculated fill ups. (That is a tough one, the tank holds 75 gallons! Really really bad on the wallet too.)
It's great for vacations though. 700 miles between fill ups.
1993 Fleetwood Flair
Details: The Beast - 1993 Fleetwood Flair includes kitchen sink Fuel Economy - EcoModder.com garage