850+ Miles per tank

[bigfordfan]

I decided to conduct an experiment the other day while on a trip from D.C. to NYC. I reset my average mileage counter on the highway after getting up to speed...

 

Weather: 80's and clear

Speed: 55mph (its actually the speed limit for most of the trip!)

Miles: 55

Average Gas Mileage: 55

 

So at 55mph, I was averaging 55mpg, and the rest of my 220miles trip, I maintained this. Just yesterday I tried to replicate these same numbers on a trip from NYC to Providence, RI and achieved about 47mpg going 55mph (again, its actually the speed limit for most of the trip), but the weather was cold and rainy.

 

I knew the sweet spot for the car was anywhere from 50-57mph, however, I had never tested it so specifically. I'm currently on track to get about 850 miles on this tank (I routinely get 700+), and I usually fill my tank about 15.5-16 gallons, so theoretically, there would still be another 40-50 miles left to empty if i drove the car to empty, which would be almost 900 miles on one tank!

 

Has anyone else seen numbers like these and what do you do to get these?

[lolder]

There's really no sweet spot for the FFH. Slower speeds always yield higher mileage and warmer temperatures yield higher mileage up to about 95 d. F. when AC loads start to increase significantly. The car gets 45 mpg at 50 mph and 60 d. F. Increase mpg 0.2 mpg for each 1.0 d. F. increase. Decrease mpg 0.6 mpg for each 1.0 mph increase. Your 80's day ( 85 ? ) at 55 should yield 47 mph. Tailwinds or moderate traffic ( which cause tailwinds ) could account for the difference.