EPA posts its 2018 2-Door JL Wrangler MPG figures (3.6L V6 Pentastar)

DanW

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The wight impacts highway MPG but not city? Thats now how it works. It should be the reverse.

Telling you, something does not add up.
It is more complicated than it appears. The highway mileage may be generated at a more efficient rpm range for the engine, while the city cycle may have it more often running at rpms where it is less efficient. Driving style is a huge variable, too. You can do a lot with hypermiling in a manual, especially if you know the right gear and right rpm for certain speeds. For example, it took me a good while to figure out that 5th gear at 45-50mph in my JK was better than 6th, which put it at a lower rpm. It is a small difference, but the 3.8 liked to be running at a little higher rpm at that speed. Of course, hills can play into it, too, and pace of acceleration. There are just many, many ways to play with a manual and get better mileage. An automatic doesn't give you as much ability to play around. However, the newest autos are VERY efficient and really hard to beat with a manual. It didn't used to be that way, but it is now.
 

macintux

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So they expect me to believe a 2 door Rubicon on 33s is going to get the same MPG as a Sport on roller skate tires?
What "they"? I've not noticed Jeep nor the EPA break it down by model.
 

DanW

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My knowledge of how automatic transmissions work is limited but I have always thought a properly geared manual is as good or more efficient than an auto. The reason autos need transmission coolers is because they create more heat which is lost energy, they also require a fluid pump which is absorbing energy.

Manufacturers have focused on autos and most have not updated the gearing of manuals to complement the higher torque motors we have today. If you look at final drive ratios (overdrive x axle ratio) most manuals are geared shorter than autos offered in the same vehicle with the same engine and don't optimise the torque of todays engines.

EPA testing methods also influence the numbers we are given. They changed their methods/formulas in 2008 and the Honda Civic changed from 40 mpg highway to 36. We were told it was to better reflect real world driving. Soon after there were media reports saying hybrids had a tough time achieving the EPA numbers and non hybrids easily exceeded them. Think there was another agenda behind the EPA changes?
Of course there is an agenda. That's why a large full-sized pick up truck can get a 3 star safety rating and a mini can get 4. However, let's crash them into each other and see which one the regulator wants to be driving.
 

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Don’t forget those numbers are “inflated” by the addition of ESS
 

DanW

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Don’t forget those numbers are “inflated” by the addition of ESS
Maybe not. TFL Car got better than EPA mileage out of the 3.6/auto JLUS they drove from Arizona to Colorado.
 

The Great Grape Ape

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Don’t forget those numbers are “inflated” by the addition of ESS
ESS would inflate city MPG, not highway MPG, so for the biggest surprise ESS would play no role.

BSG would be similar for the 2.0T, where the benefits would be in the city not the highway.
 

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I'll be interested in that, but then I'll squander it for 35's on the Rubi. Still, I wouldn't be surprised to see it pull 20mpg on the highway with the 35's, or maybe 19.
 

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It can, but it’s rarer. It’s also an open ended statment, because they can weigh more, have higher rolling resistance as well as change ground aero, although the later likely not affecting the Wranglers.

There have been a few looks at this, and the thing that always stuck in my head was the impact on acceleration, but as you can see from C&D the weight and size increase also impact fuel economy, though obviously this is their loop and not just cruise-controlled straight-line highway driving, but it would likely be more reflective of that than EPA’s spikey low speed highway tests.

https://www.caranddriver.com/features/effects-of-upsized-wheels-and-tires-tested
 

Euro JEEP

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Why has no engineer come up with a transfer case with an overdrive kind of gear?
As we can't change the final diff gear on the fly, why couldn't we do it on the tranny? If you are looking for better mileage you would go with a Sahara with 3,45 gears. If you want to run bigger tires and better off-road abilities you would go with the Rubicon and the 4,10 gears.
Now just as you can alter the end ratio with 4LO on the tranny for low speed crawling, why can't they figure out something similar for higher speeds?
 

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The wight impacts highway MPG but not city? Thats now how it works. It should be the reverse.

Telling you, something does not add up.
It also means the highway tests are more accurate. But why would it be the reverse? Do you think a loaded truck consumes the same amount of fuel as a when it's not loaded?
 

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It also means the highway tests are more accurate. But why would it be the reverse? Do you think a loaded truck consumes the same amount of fuel as a when it's not loaded?
This is a great point: There is a hypothesis that, "Those that are Loaded in Colorado do consume much more".:stop::angel:
 
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