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Going to pick up a new 2013 rubicon with auto tranni, how big of a improvment is the 4.10 for off roading? How much will it kill my mpg?
 

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It's Friday again!
 

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Yikes :eek: I get better mileage than that and I run 35" tires, lift, and my lower plastic skid has been removed.
Me too. Plus, I drive like a carjacker. Get high 15's, low 16's generally...
 

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You're only talking a couple hundred RPM difference. The only place it's going to kill your mileage is on the interstate highways. Otherwise, it'll actually do better around town and on the trails.
 

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Lot of cash for swapping ratios for f-all difference between those ratios if you had to. Gladly you were wise on initial purchase.; ) enjoy your new rig!
 

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I have 4.10, but would get 3.73 next time. Since it's a rubicon it comes with a 4:1 transfer case. So offroad in low, it winds out quickly. If it wasn't a rubicon and had the 2.71 case, 4.10 would make more sense.

4.10 on the freeway drinks a lot of gas. If you were going to run 37's though, 4.10s would be my choice.
 

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If you plan on getting bigger tires then get 4.10. And most of us end up with bigger tires in the end. I found that once I regeared mine to 4.88, that bigger tires actually worked better with mileage. My last set of tires were .72" taller then my current set and I got 1mpg more with that tire. Also towing benefits from the 4.10 over the 3.73

If you never plan on getting bigger tires, then the 3.73 will get you by but it seems that modding a Jeep is an addiction and bigger tires just seem to happen in the end. I said I would never go lareger then 33's but my next set will be 35's
 

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We get 18-19 with 3.73s and 33s. If a Rubicon on stock tires is only getting 15 there is something wrong.
 

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You're only talking a couple hundred RPM difference. The only place it's going to kill your mileage is on the interstate highways. Otherwise, it'll actually do better around town and on the trails.
Agreed, highway mileage is horrible. I commute daily with mostly highway driving and I'm averaging in the high 15's



Its alway hard for me to believe guys that say they are getting 18-19 running 4.10. I'm completely stock, always try to keep it under 3k rpm (Eco mode) and The absolute best average I ever saw was in the low 17's. I have actually been reading that guys running 33's with 15" rims are getting better mileage because the RPMs are much lower and the 4.1 seems to be better paired with that set up than it does with stock.
 

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That could just be based on the weight of the foot on the accelerator.
Yes, but that isn't the fault of the vehicle. That is the driver only getting 15, not the vehicle only getting 15. A Honda Civic will get 15 if you flog it hard enough.
 

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Yeah, I mean, with 3.73s and stock tires I was turning 2,300 RPM on the interstate at the speed limit. So with 4.10s I'd have been turning at least 2,500 RPM or closer to 2,800 RPM if I was speeding just a little bit. That is insane RPM to be turning when you've got 285 horsepower under hood. It's a waste of fuel and it's hard on the longevity of the engine.

That's why you should only do 4.10s if A) you're sure you're going to run larger tires or B) you're sure you won't be on the interstate highways much.

I honestly feel like 3.55 would be a perfect ratio for these JKs in stock form...but that isn't offered anymore. So I got 3.73s.
 

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Agreed, highway mileage is horrible. I commute daily with mostly highway driving and I'm averaging in the high 15's



Its alway hard for me to believe guys that say they are getting 18-19 running 4.10. I'm completely stock, always try to keep it under 3k rpm (Eco mode) and The absolute best average I ever saw was in the low 17's. I have actually been reading that guys running 33's with 15" rims are getting better mileage because the RPMs are much lower and the 4.1 seems to be better paired with that set up than it does with stock.
Believe it. I routinely get 18-20 mpg with my 2dr 6spd. 3.8 Rubicon, hwy, doing the actual math. I'm running stock tires and wheels with off road bumpers and a winch. Any JK getting only 15mpg that's basically a stock set up, something's wrong.
 

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Its alway hard for me to believe guys that say they are getting 18-19 running 4.10.
I routinely get 18+ mpg in my stock JK...which is an '09 with the 3.8 liter engine in it!

I actually expect my MPGs to go down in my new JK because it's an automatic. :eek:
 

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If your going to get bigger wheels, 4.10 is a no brainier. If your going with the stock wheels then I would consider how much interstate driving your going to be doing, and what kind of off-roading your planning on doing. With mud and sand the transfer case is pretty darn low.

GEAR TO MPG GUESS
After reading through about a dozen MPG threads my personal guess is that the average mpg for road driving work out close to this.
3.21 = 21
3.73 = 19
4.10 = 17

4:10 MPG AT RPM RANGE
I've got a 2012 6-speed manual Rubicon with the stock wheels and 4.10's. I did a road trip a few months back, and I tried to find the best speed for the highest mpg to pass the time. I used the AVG MPG off the wheel to test resetting every so often at different speeds. This is not exact but the best of my testing ability and memory. They are all 6th Gear on very flat 1-65 Indiana interstate.
80mph - 15.5 mpg - 2750 RPM
70mph - 17mpg - 2400 RPM
65mph - 19mpg - 2200 RPM
45-55mph - 22mpg - under 2000 RPM
 

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Believe it. I routinely get 18-20 mpg with my 2dr 6spd. 3.8 Rubicon, hwy, doing the actual math. I'm running stock tires and wheels with off road bumpers and a winch. Any JK getting only 15mpg that's basically a stock set up, something's wrong.
Sorry, I don't. How are you calculating your MPGs, the trip computer? According to my Jeep's trip computer I'm almost always in the 17's but in real world I'm far from it. Even with a manual transmission, I'll believe high 17's but that's it. No where near 20, sorry.

The fact is that the 4.1 ratio will be spinning at higher RPMs if your running stock tires, that equates to more gas. If your consistently on a highway that means worst gas mileage, simple as that. You can try to offset that obviously by not over revving and trying to keep it on the highest gear but no matter what you do, you wont be able to beat the physics.

I religiously keep track of my MPG, through real world numbers at every fill up, the only factor that deviates the mileage is fuel blend switch-over from summer to fall and the quality of gas. I was seeing a 1-2 mpg fluctuation when I switched from Wholesale Club (BJs) gas to Exxon. Sure the wholesale gas was a couple of cents cheaper/gallon but I was losing mpg and it was a wash so I just use the same Exxon gas from the same station and things have been steady.
 
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