Just posting up my last trips actual driving in my 2018 F150, 4x4, 3.55 gears, all stock, 3.5 twin turbo ecoboost, crew cab 5.5' bed from Cheyenne to Post Falls ID and Yelm WA.
I did not tow or carry a load in bed, besides a jerry can.
2605 miles round trip, all at an average of 73 MPH, just about all on cruise control and AC on.
Burned up 139.1 gallons regular gas. Gas was from a low in Livingston MT at 3.18 to 3.45 in Post falls ID.
19.05 MPG averaged with last fill up in WY. 36 gallon tank
Drove great and no issues at all. I have a tad over 57,000 miles on it as of today.
Dont believe what the trip gauge ever says as its always off by 1.5 to 3mpg.
It read a high of 24.3 in WA to a low of 17.7 from Post Falls to Missoula.
Going to Post Falls from Cheyenne I averaged 20.1 mpg total, same from Post Falls to Yelm.
All my low MPG was my trip back, thus effected my total average.
Steady winds from ID to WY was at 25 to 45mph, all side winds, so that had a effect on MPG.
Going up to ID weather was nice and calm.
Truck pulled great in all the mountain passes, up and down.
At 73 mph I get my best mpg overall and I am not racing with others as I like the in between space this way with no having to pass, speed up or slow down.
My highest speed was at 80 mph to pass a bunch of drivers who just could not keep away from clogging the road up, passing me, slowing down and all over with other drivers. I don't need to fly down the road my self.
Hope this helps any 3.5 drivers or looking to buy a F150 with such motor.
Last edited by 5spd; 09/20/21.
