One thought... even being that the LOM is usually 6% off, have you re calibrated your speedometer after going to the 35 inch tires? That will also cause your trip odometer to under report distance traveled.


Going to 35s from 31s or 32s, when you think you're driving 75 you're actually somewhere in the 80's, thus reporting less mileage and affecting your mpg calc.

Just did a 9K mile road trip. The LOM was off initially by over .6mpg but with my larger tire size installed, the errors canceled and now reads within .2mpg, calibrated against GPS. Every fill up logged, overall very consistent. With a popup camper loaded I lose 3-4mpg driving 55 vs 75 due to wind.

My truck is stock. This morning my truck took 31.2 gallons to fill while the lie-o-meter indicated only 28.1 gallons was used. Total mileage was 512 miles. Showed about 2mpg better than I actually got.

Everyone, you do realize Ford says this will give you an ESTIMATED mpg.

If this really bugs you consider this, the FDA allows the meters which diabetics use to measure blood sugar only have to be accurate to within +/- 20%. This is a medical device which can lead to using the wrong amount of insulin (life threatening).

So this really is nothing to worry or go crazy about.

Lie o meter
 

It's summer time. I suspect we loose a fair amount of gas to evaporation especially over several days.

Mine is usually off by 1.2mpg. The computer reading higher than actual. Kind of boggles my mind with today's technology how this can't be a lot more accurate.

It would take a flow meter to be precise. Given all the dollars Ford tries to save by spending here, skimping there; I'd think this is an area where they skimp. It's more of a convenience than anything.

When I got the truck (exactly one year ago today-13,103 miles) all I could do was stare at the lie-o-meter and try to get better MPGs. I've never reset my trip 1 and it stays between 21.3 and 21.5. Pen and paper its more than 20.

With what I've done to the truck, I'm happy. Now all I have on that screen is MPH and I occasionally check tire pressure. I just drive.

mine is always about 10% worse on a hand calculation.

The MPG calculators are dead on in every other car I have owned. It's not hard to get it right.

You're joking right?

My past experience has been the same; they have all been very close to actual hand calculated mileage - within 0.5 mpg at most. I haven't checked the truck yet but really expect to find the same.