Gearing Change and MPG??

[JAC34]

Hey all,

I am looking for some feedback on my scenario as I am considering upgrading my 2018 JLU Sahara V6 to a newer model.

I put a lift kit and 35" tires on mine when I bought is used in 2020. The original gearing is still on, I believe 3.73?? I only drive this about 5k miles/yr, more of a fun weekend car and also bought it for a tow vehicle behind my motorhome (flat towing makes the popular for this reason).

Not that I am too concerned about MPG, it's a Jeep, I know not what you look for in fuel efficiency. But with mostly running this around town and not much highway, I'm averaging 13/14 MPG. When stock tires were on, was prob getting 17/18. So, that is what caught my eye with the 4xe, in addition to the massive torque on that thing. Now, I know all the issues with them including the recent 68C and 78C recalls, but their price point is attractive as a used model b/c they have dropped so much in value. Also not opposed to going to the 2.0 turbo or another V6 drivetrain. So here are my questions.

1. Does changing the gearing ratio improve MPG? If I went to different gearing on my existing Jeep, would this do anything for MPG or is it mainly to help the transmission shift smoother, etc.
2. If I go to a new unit, looking at 2024s, is the 2.0 any better than the V6 on city MPG? I can look at the window stickers, but looking for real world feedback
3. Should 4xe even be a consideration solely based on MPG? Does it shake out as a big advantage if you are routinely charging it or not really worth it with all the problems?

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[Ol’ Timey Manual SWB Guy]

I didn’t think regearing to 4.56 meaningfully changed the mileage on my 6MT. I just abuse the clutch far less now. As they say, YMMV… especially at high highway speeds. Since mine is a 2dr, I don’t drive it at the kind of speeds that the over-overdrive might actually matter. For me, it’s just how it should’ve come from the factory now.

Don’t buy a 4xe for mileage. Buy it because you like the feature set (e.g., color, accceleration, 120v power out, preconditioning). In my experience, the amount of time I spend in FORM and other weird EV modes may limit the efficacy of Stellantis’ mileage claims on the Monroney sticker anyways.

Yes. I have both.

 

[grimmjeeper]

1. Yes. Gears and tire size go hand in hand. Change one and you should look at changing the other. Bigger tires are harder to turn so you need the boost in torque from the gear ratio to help you get moving. Also, bigger tires rotate slower (fewer revolutions per mile) and the shorte (higher number) gears compensate. Getting your engine RPMs back in the sweet spot on the highway, and having the extra push to get the Jeep movin help. But it's all help to a point. Don't expect miracles.

2. I have heard the 2.0 is better but I have no first hand experience.

3. The 4xe has so many technical problems that it's been discontinued. I wouldn't recommend one.

 

[JAC34]

I didn’t think regearing to 4.56 meaningfully changed the mileage on my 6MT. I just abuse the clutch far less now. As they say, YMMV… especially at high highway speeds. Since mine is a 2dr, I don’t drive it at the kind of speeds that the over-overdrive might actually matter. For me, it’s just how it should’ve come from the factory now.

Don’t buy a 4xe for mileage. Buy it because you like the feature set (e.g., color, accceleration, 120v power out, preconditioning). In my experience, the amount of time I spend in FORM and other weird EV modes may limit the efficacy of Stellantis’ mileage claims on the Monroney sticker anyways.

Yes. I have both.

Do you have 35 tires on the 4xe? will definitely be going to 35s so if that makes electric completely useless I may just go to gas model

 

[Maverick909]

correct gearing will help. That's why the factory offers the jeep with the 2" lift 35's and 4.56 gears.
you're currently running 35's on factory 3.45 gear ratio. you must be driving an auto. With my 6spd manual even moving up from the sport 31's to the rubicon 33's the jeep wasn't sluggish and not fun to drive with terrible mileage. Ended up moving up to rubicon axles with 4.10s and the 33's felt good. put 35's on with 4.10 gears... jeep was back to sluggish and no fun to drive. jumped to 4.88 gears ( knowing i would go 37/38") tires. ran that on the 35's for 6 months that felt great. tons of power with little gas pedal but highway took a MPG hit. now with the 37's and 4.88 i can avg 17-18 highway and 14 on the streets. like you i do not daily my jeep and it only sees driving to and from trails. last year i drove 600 miles to the rubicon running 18-19 mpg. anyways, all in all 4.56 would greatly help you out with your jeep

 

[James Westfall]

Do you have 35 tires on the 4xe? will definitely be going to 35s so if that makes electric completely useless I may just go to gas model

Did you calibrate your speed pulse when you put on the bigger tires? If not your MPG readout is lying to you. Also, how heavy are the tires you put on? Increase in tire weight is the biggest driver of fuel mileage loss. Gearing can affect MPGs, but it's not really until you get pretty far off optimal. Going from 33s-35s generally isn't enough to be a problem.

 

[Ol’ Timey Manual SWB Guy]

Do you have 35 tires on the 4xe?

No. Personally, I have ~32.75” factory tires on both my Jeeps currently, since you’re asking. But there are many threads here with options.

… definitely be going to 35s so if that makes electric completely useless

Been on any escalators recently? Electric motors have plenty of low end torque. That’s why Teslas beat drag cars at the dragstrip. So I’m not sure what “completely useless” means here.

I may just go to gas model

That’s certainly an option.

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