Gas milage and drivability of 4.10 Rubicon gearing vs 3.45 Sport gearing

Quigley

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I have a question for the group. What is the real world difference in gas milage of the JL Rubicon with the 4.10 gearing vs the Sport S with the 3.45 gearing. Since I believe most Jeeps spend over 95% of their life on the road, gas milage is a long term cost after the sale.

Any thoughts?





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TroyBoy

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Jeep4Life

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I am hoping it will be as good as the guys at TFLcars got when they test drove (road tripped) with the Sahara. :fingerscrossed:
 
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Quigley

Quigley

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I am hoping it will be as good as the guys at TFLcars got when they test drove (road tripped) with the Sahara. :fingerscrossed:
What was their actual mpg? Was it with the auto ? 3.45 gearing?
 

JimKrrk

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The Rubicon comes with taller, wider, and heavier tires. The higher mounted front fenders and slight extra body height also are not as aerodynamic. It needs the couple hundred higher RPM engine speed to put it in it's highway 'sweet spot' instead of feeling sluggish and constantly shifting the transmission.
 

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what about the manual i think it is widely used but not sure and what kind of mileage can i expect? Not that it matters I am only getting 12-14 with my jku lifted bumpers winch heavy stuff and 315-70-17
 

badtux

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what about the manual i think it is widely used but not sure and what kind of mileage can i expect? Not that it matters I am only getting 12-14 with my jku lifted bumpers winch heavy stuff and 315-70-17
I would expect roughly 1-2mpg better with the JL than with a similarly built JK due to the 8 speed and better aerodynamics. It's not an economy car.
 

The_Phew

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Gearing aside, the Rubicon weighs what, 250 lbs more than the Sahara, and a lot of that is unsprung, so it's even worse than that as it relates to fuel economy in the city.

BSG on the 2L turbo and '19+ V6 will help a lot with MPG. I had an F30 BMW 3-series that was a pseudo mild hybrid system (only 12V and no motor, but it had a high-current alternator that was smart enough to kick in when coasting downhill or braking), and I got insane mileage on the highway (43 mpg one 100 mile trip). iDrive would tell you how much energy was recovered by the system as you drove, and it wasn't insignificant. 48V and a true motor/generator should be quite impressive.
 

liquids

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The new dual clutch auto is going to be very competitive with the manual. There are almost no wasted rpms with a dual clutch. Even with that, though, the 4.1 gearing is going to reduce your mileage by about 19% (cuz 4.10 / 3.45 = 1.19). In other words, the engine is going to have to spin 19% more than 3.45-equipped JL to go the same distance.

I've driven my '08 JK 136,000 mostly city miles with the manual, the 3.23, and the largest stock tires. I've averaged about 20 mpg in that time - 18-19 in winter and 20-22 in summer. (In the JK forums, no one but me reported that kind of mileage. Some said I was lying. whatevs.) Expect that kind of mileage with the JL on flat roads, more in the south.
 

DanW

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The new dual clutch auto is going to be very competitive with the manual. There are almost no wasted rpms with a dual clutch. Even with that, though, the 4.1 gearing is going to reduce your mileage by about 19% (cuz 4.10 / 3.45 = 1.19). In other words, the engine is going to have to spin 19% more than 3.45-equipped JL to go the same distance.

I've driven my '08 JK 136,000 mostly city miles with the manual, the 3.23, and the largest stock tires. I've averaged about 20 mpg in that time - 18-19 in winter and 20-22 in summer. (In the JK forums, no one but me reported that kind of mileage. Some said I was lying. whatevs.) Expect that kind of mileage with the JL on flat roads, more in the south.
Dual clutch auto?
 

Jeepsterfreak

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JL also includes a front axle disconnect. The last wrangler with FAD was the YJ. FAD keeps the ring/pinion and front driveshaft stationary in 2WD.

Not sure if that improves mpg over the JK but Jeep most likely added it to the JL for that reason. That's the only reason I can think of why they added it. Seems like just one more system to fail.

Kind of funny JL only gets 2 mpg improvement with new tranny, better aerodynamics, lighter frame and ESS.
 

liquids

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Dual clutch auto?
The 8-speed is an auto in which the odd gears are controlled by one clutch and the even gears by another. When shifting from, for example, first to second, the transmission already has second in position to immediately receive torque when the “odd clutch” lets go of first. The transmission then lines up third gear so it is ready to receive torque when the “even clutch” lets go of second.
 

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