How'd I do it? By keeping my foot OFF the gas pedal.
I got off the main highway (i10) where the speed limit is 75-80mph and took a parallel country road (rte 180) where the speed limit was 60mph.
Then, I did the most difficult thing... I set the cruise control at 50mph and sat there for almost 3 hours watching the scenery drag by.
During the long ride, I pulled on to the shoulder numerous times allowing the built up traffic behind me to pass. In retrospect, the MPG test probably wasn't the safest part of my trip or anyone elses that got stuck behind me.
We crept in to Baton Rouge last night where I went directly to fill up the gas tank... 121 miles using 8.7 gallons. 13.9mpg. There was a pretty constant wind from the side that probably slowed us down some. I think I could get 15mpg on a calm day or maybe even 16mpg with a tail wind?
So far our MPG results are...
50 mph = 14 mpg
60 mph = 12.5 mpg
75 mph = 11 mpg
Steep mountain driving in Az. = 7-8 mpg
Driving into a pretty severe headwind across rte 40 in Texas = 7mpg
Tigger says... "All these numbers make my head hurt!"