naimads

Im sure this topic is somewhere in this forum but I couldn't find it on a quick search......

I'm getting around 12.8 mpg while driving 75% Hwy (75-80mph) and 25% city. 13.3mpg hwy only. Cruise Control driving. Hand calculated, not using the computer calculated mileage.

I have a 2017 Ford F150 Platinum 3.5L Ecoboost FX4 with ~11,000 miles, 10 speed, 3.55 diff, leveling kit, and nitto ridge grappler 295/60r20s that weigh about 65lbs each.

The truck is rated 17city/22hwy/20 combined. I would expect a 10-20% reduction with my setup but I'm seeing around a 40% reduction.

When I took it in for the 10,000 mile service, I had them look at the throttle body so they ran a diagnostics and said everything is fine.

What do you guys think? And whats the setup for the Ford fuel economy ratings?

13_F150

That's horrible.
2016 3.5 ecoboost 6 speed with 3.55s 157" wheelbase FX4 on heavy wide 305/55R20 and Iieometer claim 16.4, hand cal about 15.2 with same 75/25

idrive

iTrader: (3)

70-80 mph is a killer.

The level with the heavier tires coupled with speed and winter gas pretty much explains it.

Tom_with_a_Truck

Did you account for the change in tire diameter? If the new rubber is larger in diameter than the stock tires, your odometer will under-State the miles driven. If that’s the case, you are probably driving farther than it’s saying you did.

i would use a GPS or cell phone, and check the accuracy of your ODO.

NASSTY

Are you hand calculating or is that what the lie-ometer is telling you?
If you haven't corrected the speedometer for the 34" tires the lie-ometer will lie even worse.

naimads

I calculate gas mileage by hand as I know the computer will be off.

Tom_with_a_Truck

What size tires were originally on the vehicle?

naimads

275/55r20s I believe.

naimads

My computer tends to calculate about 1-1.5 mpg better than my hand calc.

dajohu

I get double that. Guessing it's a combination of speed, taller tires, heavier wheels and tires, aggressive tread of the tires, leveling, and likely too aggressive of acceleration. Driving like a grandpa helps lol.

Setup for fuel economy ratings is completely stock, tires and all, and likely 60-65 mph hwy. Wind can be killer too, driving into a headwind can knock off several MPG compared to a tailwind or calm day. Even in my raptors (had a 5.4 and 6.2l) I was able to get better than the rated amount by staying stock and keeping speed down.