Kingofwylietx

I keep a detailed record of my mileage and exact number of gallons dispensed at each refuel.

Vehicle: 2017 F150, SCrew, 4x4, 20", 3.55, 3.5EB, 7500 miles on the clock.

Environment: my driving approx 50/50 mix of highways at 75-80mph (75mph speed limits) and daily commute of 10 miles with around 15 stoplights/ stop signs.

Computer says: 19.9 lifetime average
My spreadsheet says: 18.26 mpg lifetime
(my spreadsheet is at work, but my memory is 99% sure I'm right...I'll update my post tomorrow if I'm wrong)

I have a tonneau cover, but I saw no gain in mileage from installing it. I put it on around the 2000 mile mark.

deserteagle69

I also input all the fuel data into a spreadsheet. My F150 is just about to turn 15,000 miles and overall, since I brought the pickup home in May of 2016, the spreadsheet tells me the mileage is 20.88 mpg. Yet as I'm driving along, even on I-80 where the speed limit is 80 mph, my dash display tells me I'm getting anywhere from 22.5 to 24.5 mpg. That's why I question some of the mileage figures I see posted. I have NEVER filled it up and had the dash display indicate lower fuel mileage for that period than what I hand calculate.

Kingofwylietx

Me either. I wish we could adjust it, I'd make it much more accurate.

Well, except when a Ram or Chevy friend is in the truck.....then I'd dial it up to add 10mpg to the actual.....and then go on about how I normally get much better mileage. Bwah-ha-ha-haa

sRide

Anyone build a function into their spreadsheet to record the ambient temperature at fill-up and apply the coefficient of thermal expansion? Asking for a friend....

Slowtrucker

That extra mile won't hunt...


Even with the 36 gal tank.

Kingofwylietx

I can say that my spreadsheet is for convenience, it's not a hobby.

Wouldn't your friend's suggestion of a simple ambient temperature conversion actually require the operator refueling the vehicle to measure the temperature of the fuel as it is pumped into the vehicle? Otherwise the ambient temperature used to calculate thermal expansion would be meaningless.

If your friend's hypothesis of onboard calculations being more accurate is correct (you didn't state this, I'm just reading into your question), then would that mean the computer should be quite accurate on days the ambient temperature matches the underground storage temperature of the fuel where they bought the gas?

Ask your buddy....if we were to greatly exaggerate the thermal expansion of fuel so that 1 gallon pumped at the station became 10 gallons (volume increases, not energy density) in the trucks fuel tank, due to thermal expansion...what would the result show on the MPG screen of the truck?

Beyond that discussion, you would have to factor in the accuracy of the flow meter on the gas pump on the day it was pumped (flow meters are finicky things and their accuracy is determined at a particular temperature...any deviation from that temperature and a narrow range of flow will further reduce their accuracy). The same holds true for the systems on the truck.

My truck still seems to be quite an optimist.

Stangman516

So far I've been between 17.2-17.6 MPG hand calculated, mostly commuting on highway but with traffic. The computer consistently reads about 1.5mpg better than I'm actually getting. Best I've seen was just shy of 20mpg on my last road trip which was not ideal conditions either with lots of traffic. Definitely beats my super duty which was a pretty consistent 14mpg.

crazygrow1

Jealous of those getting 20+. I don't hand calculate, just the computer has said pretty consistently ~17.3MPG even when I force myself to drive very relaxed for a few tanks. Not sure what I'm doing differently that is costing me 3MPG. I'm about 50/50 city/highway driving.

Eurasianman

Here's mine. 17' XLT SCREW FX4 3.5 EB with 3.55 I probably could have gotten up to 21+ if I stayed consistently at 70 MPH.

Kingofwylietx

My lifetime, calculated by dividing miles by gallons, is 18.234 mpg.
Best tank ever: 19.259 mpg
worst tank ever: 16.974 mpg