Highway MPG getting progressively worse

[redline]

I am getting better mileage as the truck gets more mileage on it … run 18“ after market winters and i get 2 miles better then the factory 20”

I think I am going move to 18” summers as well.

I find wind really negatively effects mileage in this truck …

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[Dizz]

Above 55mph sucks gas
Above 70 double sucks
Any change from stock tires bad for mpg
As to tire pressure I only watch even tread wear and adjust weather it’s 25 psi or 45
Tires tuners and lifts all destroy mpg
Winter fuel blends hurt as well
Head winds and tail winds can cause 25% loss or gains

 

[EcoB259]

I am getting better mileage as the truck gets more mileage on it … run 18“ after market winters and i get 2 miles better then the factory 20”

I think I am going move to 18” summers as well.

I find wind really negatively effects mileage in this truck …

If you do not recalibrate your speedometer when you change tire size it will give you false readings.
Going to a smaller tire will cause your speedometer to read a faster speed than you are actually going.
You may be getting better mpg because your driving slower.

 

[TheGoatman]

Yup unfortunately badass tires hurt mpg. Goodyear territory AT. These look more aggressive than they are. They work like an oem tire.
good mpg, quiet, and soft on the potholes.

Def need to be cruise control, set to eco, at around 70mph to get north of 20mpg…the whole trip. No flooring it out of toll booths or passing. One or two of those and it’s game over too

 

[redline]

If you do not recalibrate your speedometer when you change tire size it will give you false readings.
Going to a smaller tire will cause your speedometer to read a faster speed than you are actually going.
You may be getting better mpg because your driving slower.

I am running all stock sizes, i am sure they will very slightly but not enough to matter

 

[2BigDogs]

I'm seeing the same thing, however my 2023 Limited PB, 6600 miles, is bone stock. My previous truck, 2018 FX4 3.5EB with 20 in wheels, would consistently average 21.8 mpg year round on the highway running 75 - 80 mph. The new truck averages 18.5 at the same speeds. Around town is similar, 3 mpg less. Supposed to be better mpg with the hybrid... NOT!

 

[elaudermilk]

Agree here. Drove to central Missouri from Dallas last summer - tested theory out… staying under 73 mph has a dramatic effect on mileage. I’m leveled with Toyo at3s.

 

[mtmiller302]

Third winter on my '21 PB. Winter MPG is definitely lower than summer. I wouldn't even think about MPG until next summer.

 

[spiritrider1]

Keep in mind, everyone's experience will be different. The PB is not a Prius. It's main objective is to provide a system of supplying a power source for Pro Power. The side benefit is supplemental energy to augment the engine which helps reduce fuel consumption.
Every truck is specc'd differently. Different weights, tires, axle ratios, capacities, weather conditions, altitudes, hills vs. flat land, etc.
The mileage computer needs to be calibrated. There's a way to do that in the dash engineering mode. The factory mpg setting is the same on all trucks, set at an AFE Bias of 1000. Yet there are trucks delivered with 17" - 22" tires of different widths. Thats' a huge variable.
Either way, if you don't correct the AFE, then at least do manual calculations at every fill-up.
Winter fuel blends and octane will affect mpg. High altitude and using 85 pump gas will give you a much different result to using 93 at sea level.
Spirited driving is rewarded with invigorating performance - and an mpg hit. Turbo's can be efficient OR powerful. Finding that middle ground is not easy but most of us PB owners have found 70mph on level ground returns respectable mpg.
2 1/2 years of consistent 25 mile travel to work on 40/60 city/hwy in a variety of weather conditions and seasons provide a very good baseline. I'm averaging 23.2 over 42K miles. Each oil change I reset the #2 trip computer and let the mpg's carry forward while I reset the #1 trip computer at each fill-up. I also use the Fuelly app to keep track of consumption and maintenance.
A couple intervals were in the low 22's due to cross country driving with a full truck and trailering through Texas hill country.
I, for one, am happy to have a 430 hp, 570 tg 1/2 ton 4x4 truck that gets within a couple mpg's to what my brother does in a 4 cylinder Subary Cross Trek. AND with an on board generator.

 

[EcoB259]

I am running all stock sizes, i am sure they will very slightly but not enough to matter

I thought you were switching from 20s to 18s if so, recalibration would be needed to be accurate.

 

[TheGoatman]

I attached a pic of the tire. They are less expensive so I am ok with changing them more frequently if they don’t last as long as a ridge grappler.

I also noticed this tire in this size was chosen for the 25+ new Tahoe/suburban z71.

During my trip, I ran through a bad downpour overnight for 4 hours. They are new but they worked great.

imho this is the most aggressive looking tire without giving up ANY comfort and on road quality.
I don’t have experience off road but do look more capable than the oe hankook and pirelli

 

[westbayou]

Guess I wasn't clear in my original post. The gas mileage has been dropping although NOTHING has changed. Even with the level and tires which are .2" taller than stock (also a 33"), I was getting over 20mpg on the highway until recently. At this point my only guess is winter blend gas?

 

[RossRR]

400 mile round trip yesterday; half at 75 mph, half at 60 mph with a 12 mph crosswind and I got 18.0 mpg; totally stock and on cruise control 90% of the time. That same trip gets 20 mpg in summer months. Of course summer is 80 F degrees and yesterday was 22 F degrees so a little different than Florida.

 

[RickBullotta]

I'm curious if anyone is experiencing steadily decreasing highway MPG's as they put more mileage on their trucks. Just got back from a 550 mile round trip on mostly highway, and averaged a dismal 16.8mpg at around 75mph. I've got a Platinum FX4, leveled with 305/55/20 tires so almost stock size diameter. Just flipped 14K miles. City driving I'm still able to get over 20 on average, but I hit the highway and it drops like a ROCK. Overall I drive like a grandma but cruise between 75-78. When I had 5K miles on it 20-21mpg average for highway driving was the norm. I'm at a loss as nothing has changed in that time.

Did you put A/T tires on? And a 2" level definitely affects aerodynamics.

 

[spiritrider1]

Cruise will often give you worse MPG unless you are on very flat roads! Any hill will request the engine spool up to maintain speed. I don't use cruise in hilly areas because of this. I use physics and nature to help instead. Going downhill, I'll let the truck build up and carry more speed. As I'm going up the opposing hill I'll let speed bleed off then gradually apply throttle to keep it within a safe and appropriate speed for that part of road (i.e. not too slow!).
Having driven a lot of Texas Hill Country roads, you get pretty used to this technique. Trust me, It saves a lot of gas when doing 200+ miles of driving from San Antonio to N. Texas up FM-281.

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