Huge MPG change?

[ShadowsPapa]

I actually found that cruise control gave crappy MPG vs. using my own foot. About a 2 MPG difference.

That will depend on terrain to some extent.

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[Gren71]

My ride is a 2020 Gladiator Sport-S. Had 18" rims with 32" Bridgestone Duelers. I got about 18-19 MPG around town.

I added a lift kit, which should not affect anything mileage wise I would think. I got a new steel bumper. When I got the lift kit, I went to 35x12.5 Toyo's. I'm noticing my MPG is down to 15 MPG. That's about a 20% loss. Is this normal/expected?

Here is how I decided to go back to an OEM size. Give the thread a read, it may clear up some of what you are experiencing.

https://www.jeepgladiatorforum.com/forum/threads/worth-it-to-go-back.47891/

 

[Walter-new jeeper]

That will depend on terrain to some extent.

How about 70 mph on flat terrain? Even on hilly terrain I found CC was worse than my foot. This was on a trip from the Seattle area down to Arizona, then to Moab, and home. Was averaging 14 mpg on CC, could average 16 mpg with my foot.

 

[BAT]

Freedom edition here (sport s w/ steel bumpers) and max tow. I threw on new wheels and 35’s along with a lvl kit in the front. Adjusted the realistic tire size in the computer with a tazer. Currently get an average of 15mpg city and 17.5 highway (70mph tops) no other mods and hauling nothing but my wife and kid. Gas guzzler for sure. I live in Florida so it’s as flat as you can get and I feel like I drive like a grandma.

Funny because I see some of these pictures of ppl with their dash at like 22mpg+ who swear they run 35’s and are not diesel. I don’t doubt the pic but somethings got to give because I know my setup and I don’t get near that.

Me either and I don't have 35's don't want to take another hit in the MPG. Sport S Max Tow, Rubi Take off's, Arcus Bumper/skid plate with 10K Synthetic winch at about 65 lbs. I'm pretty much at around 15-16 city (35-40 mph) and highway I get about (19-20) if I stay in the 60mph range. Flatlands of Katy, TX

 

[ShadowsPapa]

How about 70 mph on flat terrain? Even on hilly terrain I found CC was worse than my foot. This was on a trip from the Seattle area down to Arizona, then to Moab, and home. Was averaging 14 mpg on CC, could average 16 mpg with my foot.

I've tried for 2 years to determine which got me better mpg....... cruise or foot. Even with my wife it was an experiment as she's a very conservative driver and keeps her own Jeep up at about 25 mpg with ease. Every time I've compared, no matter what I do, the cruise is about the same.
If I do the tricks as far as gaining speed on hills, letting it slow going up a hill and keeping the throttle light (as if using a vacuum gauge like we did years ago) I could milk it a bit but in ordinary driving on the highway, it was pretty much a wash. I tried and tried to prove "I can do it better" because I was so sure I could, and I've observed how my wife does with her Jeep.
I figured when she drove my truck it would do better. It did not.
Must be other differences...........

 

[Blade1668]

I'm "driving miss daisy" mostly type of driving trying for best mpg! why I drive 53-57 miles to and from work. I use cruise control and manual shift control (I've found to help) I try to set cruise control at 69 max best MPG found at under 70 FYI so 69 MPH at 40 it sucks more than 46 mph.

 

[paloaltan]

Sell it and get a Honda odyssey. Make all your friends jealous when you meet them at the panera bread parking lot.

lol I have both, but depending on whether or not the Panera is in a mall location...

 

[PyrPatriot]

Yep, I had a thread about it a couple years ago on the effect on performance (towing, payload, etc) with mods like larger tires, lifts, winches, etc.

Stock I was getting 21mpg mixed highway. Mud-terrain tires (same size as OEM sport) dropped me down to 20mpg. Front steel bumper and winch dropped me down to 18mpg. Adding 35" mud terrains has brought me to 16-17mpg. Performance wise we're talking 15gal per 300mi (about a fill-up) to 19gal per 300mi. That is about $10/300mi more, $20/mo more, a hit I am willing to take for having larger tires and a winch.

If I had gone down from 12gal/300mi, then we're talking $20/fill-up and if I had to fill-up once a week then yes, it starts to be more significant at closer to $1000 per year more to run the Jeep.

 

[ShadowsPapa]

Yep, I had a thread about it a couple years ago on the effect on performance (towing, payload, etc) with mods like larger tires, lifts, winches, etc.

Stock I was getting 21mpg mixed highway. Mud-terrain tires (same size as OEM sport) dropped me down to 20mpg. Front steel bumper and winch dropped me down to 18mpg. Adding 35" mud terrains has brought me to 16-17mpg. Performance wise we're talking 15gal per 300mi (about a fill-up) to 19gal per 300mi. That is about $10/300mi more, $20/mo more, a hit I am willing to take for having larger tires and a winch.

If I had gone down from 12gal/300mi, then we're talking $20/fill-up and if I had to fill-up once a week then yes, it starts to be more significant at closer to $1000 per year more to run the Jeep.

It was amazing how much the bumper change, adding the weight of the winch, skid plate and steel bumper changed mine. It was the single largest part of the loss of mpg I experienced with changes. Raising the truck a bit changed it a little, but the bumper swap and the things I did along with that were the biggest impact. The tires dropped it a little more beyond that.
The engineers knew exactly what they were doing.
Check out Chevy engineering and their wind tunnel testing. Like they say - it's not the shape of the mirror that concerns them, it's the interaction of that mirror with the rest of the side of the truck that has the bigger impact. Similar for the bumper - yeah, there's weight there to consider, yeah, most after-market do expose the fronts of the front tires, but it's the interaction of the shape of that bumper with the rest of the truck that determines drag losses. The factory stock plastic bumper is shaped a specific way - not so it in itself will be more "aerodynamic" but what happens to the air that passes it as far as interacting with the rest of the truck. The whole thing is a system, change mirrors, door handles, the shape of the bumper, how much air goes under, over, around, through, and you change mpg due to drag. Exactly where a shape is on the side of a truck has impact even if you don't change the shape of the item itself. The front bumper - raise it an inch, drop it an inch, you change how the air flows around the body.

I've said this before, I'm sure, look at modern semi tractors, the fronts of the tires are not exposed to air. Bumper and valance come way down, and curve in such a way air can't hit the fronts of tires. Same for SUVs (and I laugh at how loosely that term is used today - they aren't SUVs, people call 'em that) - the bumper and/or valance wraps around and prevents air from hitting the front of the tires. Wheel openings are no longer big enough you can see the suspension or steering between the tire and body - that's for a reason. Air hitting the front of that tire is drag. The rougher the tread, the wider and taller the tire - the more drag.
Of course the wider the tire and the more radical the tread design the more rolling resistance there is, too. Taller and wider tires mean more footprint, and more resistance to rolling.

 

[PyrPatriot]

It was amazing how much the bumper change, adding the weight of the winch, skid plate and steel bumper changed mine. It was the single largest part of the loss of mpg I experienced with changes. Raising the truck a bit changed it a little, but the bumper swap and the things I did along with that were the biggest impact. The tires dropped it a little more beyond that.
The engineers knew exactly what they were doing.
Check out Chevy engineering and their wind tunnel testing. Like they say - it's not the shape of the mirror that concerns them, it's the interaction of that mirror with the rest of the side of the truck that has the bigger impact. Similar for the bumper - yeah, there's weight there to consider, yeah, most after-market do expose the fronts of the front tires, but it's the interaction of the shape of that bumper with the rest of the truck that determines drag losses. The factory stock plastic bumper is shaped a specific way - not so it in itself will be more "aerodynamic" but what happens to the air that passes it as far as interacting with the rest of the truck. The whole thing is a system, change mirrors, door handles, the shape of the bumper, how much air goes under, over, around, through, and you change mpg due to drag. Exactly where a shape is on the side of a truck has impact even if you don't change the shape of the item itself. The front bumper - raise it an inch, drop it an inch, you change how the air flows around the body.

I've said this before, I'm sure, look at modern semi tractors, the fronts of the tires are not exposed to air. Bumper and valance come way down, and curve in such a way air can't hit the fronts of tires. Same for SUVs (and I laugh at how loosely that term is used today - they aren't SUVs, people call 'em that) - the bumper and/or valance wraps around and prevents air from hitting the front of the tires. Wheel openings are no longer big enough you can see the suspension or steering between the tire and body - that's for a reason. Air hitting the front of that tire is drag. The rougher the tread, the wider and taller the tire - the more drag.
Of course the wider the tire and the more radical the tread design the more rolling resistance there is, too. Taller and wider tires mean more footprint, and more resistance to rolling.

That reminds me, I'd say I lost 1mpg from making the bumper stubby!

 

[Bananaman]

Have you ever seen one person with Max Tow not mention it like they’re laying their 10” dick on the table?

Hey, hey, what about us diesel guys?? At least 8?

 

[TheSolarWizard]

My ride is a 2020 Gladiator Sport-S. Had 18" rims with 32" Bridgestone Duelers. I got about 18-19 MPG around town.

I added a lift kit, which should not affect anything mileage wise I would think. I got a new steel bumper. When I got the lift kit, I went to 35x12.5 Toyo's. I'm noticing my MPG is down to 15 MPG. That's about a 20% loss. Is this normal/expected?

that’s normal But the diesels are less affected
Those tires are at least 20% higher than the stock ones

 

[TheSolarWizard]

Have you ever seen one person with Max Tow not mention it like they’re laying their 10” dick on the table?

only once but he was a she or at least I think but in 2022, who even knows anymore

 

[Iamstubb]

I swapped out my rock rails for the tubular side steps. I shed a lot of weight doing that. My rough estimation is that the two steps weight less than a single rail. I swear I am getting better mileage by 1-2 mpg and this thread makes me think that is the reason.

 

[PyrPatriot]

I swapped out my rock rails for the tubular side steps. I shed a lot of weight doing that. My rough estimation is that the two steps weight less than a single rail. I swear I am getting better mileage by 1-2 mpg and this thread makes me think that is the reason.

I had those steps, until I hit a rock wheeling and cracked one. It was a good hit, minor damage. I prefer the rock rails. But yes, adding 100lbs rock rails and a 100lb horse stall mat for the bed and 100lbs of bumper and winch and 50lbs of gear, well now my 1550lb payload becomes 1000lbs payload with me in the Jeep. Yet somehow when I am on the scales I am darn near gvwr!

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