Highway MPG getting progressively worse

[westbayou]

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.

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[scott011422]

There are so so so many factors. For my 22’ bone stock 502a PowerBoost, tollways at 75mph are 18.2 on average with little to no traffic. Keep in mind that the only time I drive on the tollway enough to matter is December in Wisconsin. So it’s cold.

 

[westbayou]

Yeah, I realize there are a lot of variables, but my drives are mostly the same 115 mile commute each way, I'm in Florida, get gas at the same place etc. so pretty consistent overall outside of random weather events. I've get seen my highway mpg's getting lower and lower the longer I own the truck.

 

[Tenchi]

I have a '23 PB that is leveled with the Tremor skid plate. My MPG is still the same, however I am still on the stock tires. Are your tires much wider than stock? I doubt in FL you have to worry about the tire pressure with the ambient temp, but spot check could not hurt.

 

[Samson16]

that was a trip from Central Florida to Asheville and back in October. Hasn’t dropped so far.

 

[westbayou]

Samson: That's about what I saw last July when I went from Florida to Franklin NC, same level kit and wheels/tires.

 

[Samson16]

I doubt in FL you have to worry about the tire pressure with the ambient temp, but spot check could not hurt.

It was frigid 45 degrees F this morning and my tire pressure dropped from 39 to 33, so it does change a bit.

 

[Chili]

It's your level and tires tanking the mileage.

 

[Tenchi]

It was frigid 45 degrees F this morning and my tire pressure dropped from 39 to 33, so it does change a bit.

That is brisk for FL.

 

[Tomatoboy]

It’s almost certainly the level and the tires, not your advancing mileage, assuming your tires aren‘t low on air and you have no obvious malfunctions. What tires did you pick? They may be performing different seasonally or at highway speeds.

 

[TheGoatman]

Just got back from a 2250 mile round trip to Florida. Got 22.0mpg on 89 octane

2inch level and light 33.4” at tire

mileage drops like a stone above 72mph. I spent most of the time there

 

[mxwrk]

Just got back from a 2250 mile round trip to Florida. Got 22.0mpg on 89 octane

2inch level and light 33.4” at tire

mileage drops like a stone above 72mph. I spent most of the time there

Which tire are you running? I’m leveled on Fox 2.0’s, method wheels, and BFG 285/70/17’s. (I believe my tires are 51lbs)
I struggle to get 20mpg but can do it if I keep it at 70mph or under.

 

[Zyvin]

No stock tires are LTs, adding them adds at least 10lbs per tire. That and this truck hits a wall over 75, the more you lift the front; the more that wall mph moves down.

Off the lot is the best mpg possible. Change the antenna, lose 0.2 mpg.

 

[TRSCobra]

I find winter blend gasoline to drop MPG a bit, also check your tire pressure. Mine were 6-7psi low when I checked them the other day and I noticed a 2mpg increase since airing them back up.

 

[Eskram]

mileage drops like a stone above 72mph. I spent most of the time there

I've found that as well - if I stay just under 74ish, I do ok. Above that, it's a large brick (and below that speed too, really), doing real-world aerodynamics in your face.

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