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3.0 vs 3.6 MPG towing

NCJL

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Just finished a 600 mile round trip through Northern California while towing a #3500 off road trailer. We have done this trip with our 3.6 JLUR and now are 3.0 JLURD. Both Jeeps on Stock Gearing w/35” tires. The 3.6 is lifted/modified more than the 3.0. The weight of the Jeep’s is within #100. The trailer weight is about #300 more now (JLURD) due to added modes.

300 miles 4 lane freeway not flat with a few short grades. 60-70 MPH.
200 miles 2 lane highway not flat with several short grades. 35-60 MPH.
100 miles dirt road switchbacks up/down 5-35 MPH. A few spots 4Low. 1 spot lockers.

JLUR 12.5 MPG
JLURD 21 MPG

Comparison. 3.6 did ok. Seemed like it was always near its max capability. Would never consider this set up with 37” tires without a regear.

3.0 was awesome. Everything seemed effortless. Always felt like the 3.0 had plenty more to give. Thinking 37” tires would be ok with this setup.

MPG seemed to be directly connected to RPM.
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70% better towing mpg or overland heavy setup mpg is what a lot of folks on here were talking about when they first got amped up about the 3.0. The naysayers came on and claimed numbers like that would never materialize. My rig is closer to 40% better mpg compared to a much lighter 3.6 JLUR I had before it but I don’t tow much. Either way, yea, diesel is way more efficient under load.
 

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21 mpg is impressive. I tow a two horse trailer (with some gear in it) with my 3.6 stock JLUR and would be thrilled with 12.5 mpg. I see closer to 10mpg. I’m thinking about a diesel just because of the towing.
 
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NCJL

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Diesel is better for towing. Not just mpg. Braking! The 3.0 would hold speed on a 7% Downgrade in manual Mode.
 
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NCJL

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Just finished another trip with the 3.0 that we had previously done in the 3.6.
The only difference is the current trailer setup is probably 700lbs heavier than it was with the 3.6.
The MPG numbers were the same. The ED did about 9 MPG better than the 3.6.
This trip was to the Shaver Lake, CA area. The 168 highway to get to Shaver has about 7 mile stretch that averages 6% grade. Also has many turns. It is a 4 lane, however it is 7 miles with no relief with slowing for corners.
The UP.
The ambient temp. was about 90 degrees at the bottom. The ED pulled without problem. Happiest in the hi 2000 rpm range. The coolant level did reach 244 degrees. Never overheated. The ED could hold speed and recover from slowing down without issue. Stopped for fuel near the top. Did not shut off. Within a minute or so the coolant level returned to normal.
The Down.
ED with trans in manual mode would hold speed up to 6th gear for the most part. I did tap the brakes a few times.
The 3.6. Did not like this hill at all. Never happy. 4K RPM range to try to maintain. Down was the same. Not happy. Lots of intermittent brake use to hold speed.

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WXman

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70% better towing mpg or overland heavy setup mpg is what a lot of folks on here were talking about when they first got amped up about the 3.0. The naysayers came on and claimed numbers like that would never materialize. My rig is closer to 40% better mpg compared to a much lighter 3.6 JLUR I had before it but I don’t tow much. Either way, yea, diesel is way more efficient under load.
70% fuel economy improvement when unloaded is pretty accurate from what I've seen. While loaded it's not.

I'm not calling anybody a liar, but I think his results are off quite a bit.

I've towed extensively with the 3.6L in multiple Jeeps and two different 3.0L Gen 3 diesels. When pulling a few thousand lbs. or more, the MPG difference is actually very small. I saw 12 MPG with the 3.6L engines and 12-14 MPG with the 3.0Ls if we're talking 4,000ish lbs. of weight.

If you look at all the testing that's been done by TFL out in the mountains the story is about the same. Diesel engines lose 65% or more of their efficiency when worked hard. That's WAYYYY more than a gasoline engine will lose. Granted, the diesel is starting at a higher MPG, so it can lose more efficiency and still end up near a gas engine when towing the same weights.

I'm at a lower elevation and I see the same. Around 65% MPG loss when I hook a trailer on.

That's even true in the larger truck world. A lot of guys are buying gas HD trucks now because the gas HD trucks get the same MPG when towing, but they save $9,000 by not choosing the diesel engine option.

Yes the EcoD definitely saves fuel. No question. But once a guy hooks on a trailer it becomes a wash.
 

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NCJL

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70% fuel economy improvement when unloaded is pretty accurate from what I've seen. While loaded it's not.

I'm not calling anybody a liar, but I think his results are off quite a bit.

I've towed extensively with the 3.6L in multiple Jeeps and two different 3.0L Gen 3 diesels. When pulling a few thousand lbs. or more, the MPG difference is actually very small. I saw 12 MPG with the 3.6L engines and 12-14 MPG with the 3.0Ls if we're talking 4,000ish lbs. of weight.

If you look at all the testing that's been done by TFL out in the mountains the story is about the same. Diesel engines lose 65% or more of their efficiency when worked hard. That's WAYYYY more than a gasoline engine will lose. Granted, the diesel is starting at a higher MPG, so it can lose more efficiency and still end up near a gas engine when towing the same weights.

I'm at a lower elevation and I see the same. Around 65% MPG loss when I hook a trailer on.

That's even true in the larger truck world. A lot of guys are buying gas HD trucks now because the gas HD trucks get the same MPG when towing, but they save $9,000 by not choosing the diesel engine option.

Yes the EcoD definitely saves fuel. No question. But once a guy hooks on a trailer it becomes a wash.
My #’s are accurate.
 

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70% fuel economy improvement when unloaded is pretty accurate from what I've seen. While loaded it's not.

I'm not calling anybody a liar, but I think his results are off quite a bit.

I've towed extensively with the 3.6L in multiple Jeeps and two different 3.0L Gen 3 diesels. When pulling a few thousand lbs. or more, the MPG difference is actually very small. I saw 12 MPG with the 3.6L engines and 12-14 MPG with the 3.0Ls if we're talking 4,000ish lbs. of weight.

If you look at all the testing that's been done by TFL out in the mountains the story is about the same. Diesel engines lose 65% or more of their efficiency when worked hard. That's WAYYYY more than a gasoline engine will lose. Granted, the diesel is starting at a higher MPG, so it can lose more efficiency and still end up near a gas engine when towing the same weights.

I'm at a lower elevation and I see the same. Around 65% MPG loss when I hook a trailer on.

That's even true in the larger truck world. A lot of guys are buying gas HD trucks now because the gas HD trucks get the same MPG when towing, but they save $9,000 by not choosing the diesel engine option.

Yes the EcoD definitely saves fuel. No question. But once a guy hooks on a trailer it becomes a wash.
I agree I hooked up a 2000 lb trailer on relatively flat ground and Highways and my great MPG in my 3.0 dipped to the low teens. I hear some are getting low twenties with almost a third more weight. I only have 35 on a stock setup even if I had 33s I can't imagine I could get into the low 20s. It is rare and I was only Towing helping out a friend with a basic flat bed cargo trailer. Can't imagine adding a box trailer or something with wind resistance. Wranglers were not meant to tow. On the other hand full camping gear 10 + days high in the High Sierras Highway forestry roads averaged 24 to 26 mpg. And yes for the second time I had a Regen indicated on my ID Banks while off-roading 4low and 4hi crawled under the rig, mid regen no excessive heat as a result. If it wasn't for the gauge or ever so slight sound as a result of the regen you would never know the difference do you think for a second the Jeep engineers would create a rig capable of going remote off-road areas and then cause a forest or shrub fire as a result of excessive heat buildup from a regen. The engineers thought of everything including relocating the alternator for water forging. Keep us all posted when the 3.0 EcoDiesel fully stock, lights up dry grass or brush as a result of a regen.
 
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NCJL

NCJL

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70% fuel economy improvement when unloaded is pretty accurate from what I've seen. While loaded it's not.

I'm not calling anybody a liar, but I think his results are off quite a bit.

I've towed extensively with the 3.6L in multiple Jeeps and two different 3.0L Gen 3 diesels. When pulling a few thousand lbs. or more, the MPG difference is actually very small. I saw 12 MPG with the 3.6L engines and 12-14 MPG with the 3.0Ls if we're talking 4,000ish lbs. of weight.

If you look at all the testing that's been done by TFL out in the mountains the story is about the same. Diesel engines lose 65% or more of their efficiency when worked hard. That's WAYYYY more than a gasoline engine will lose. Granted, the diesel is starting at a higher MPG, so it can lose more efficiency and still end up near a gas engine when towing the same weights.

I'm at a lower elevation and I see the same. Around 65% MPG loss when I hook a trailer on.

That's even true in the larger truck world. A lot of guys are buying gas HD trucks now because the gas HD trucks get the same MPG when towing, but they save $9,000 by not choosing the diesel engine option.

Yes the EcoD definitely saves fuel. No question. But once a guy hooks on a trailer it becomes a wash.
If you drive the 3.0ED like a 3.6 gasser your fuel mileage will be reduced.
I learned this 20 years ago with a Duramax vs the gasser equals in the HD.
A diesel must be driving like a diesel to achieve greater MPG. This is why I bought a JLURD.
 

MIAZ

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I’ve never towed with a 3.6 as our ‘13 JK was a 2 door and that may not have been the best idea with the short wheelbase. In late April and early May we towed our 22 foot travel trailer from Arizona to Michigan. Our trailer is 3000 pounds dry and with gear and water onboard it’s about 3500 pounds. We camped along the way and did day trips from our campsite, during the towing portion of the trip we averaged 16 mpg and that included long and steep climbs in Arizona and Colorado. We mostly drove at 60-65 mph with the sweet spot seeming to be about 62 mph.
We had a lot of time and mostly drove on scenic 2 lane back roads 80-85% of the time, I was real happy with the mileage that our stock JLURD produced. It’s mileage towing the same trailer over close to the same route was nearly identical to what our 2002 F-250 7.3 liter diesel with a 6 speed manual did the previous year. The key seems to be speed, if you drive at 70, expect 14 mpg, 75-80 you’ll be around 11-12.
Yah, I know most people don’t have the slow driving option with traffic and time constraints, but with an easy gas pedal operation you’ll do good.
 

MIAZ

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An add on to my previous post. The ‘21 JLURD and the ‘02 Ford F-250 both have 3.73 gears and the Jeep with the 8 speed automatic runs about 150-200 rpm slower at the same speed as our F-250. The F-250 at 19 years old now has been my favorite vehicle, several times the thought of being buried in it has crossed my mind, but the Rubicon diesel is edging into that part of my mind now too. Longevity and reliability will be the deciding factor on that.
We also towed this trailer with a 2019 Toyota Tacoma TRD Off-road V-6 automatic. Although the truck was fine, we found that towing the mpg’s were in 10-12 mpg’s. AND, the big thing that drove me nuts was the constant up and down shifting. Dropping a gear or 2 and buzzing with high rpm all the time, constantly, we owned this truck for 22 months and I was happy to see it go.
So towing the same trailer with the gas Tacoma and the diesel Rubicon, there’s no comparison in power/torque and mpg. The Ruby is far and away a better tow vehicle for my purposes, not 20-25% better, but 2-300% better. We had our 2013 3.6 JKR for almost 6 years and had enjoyed it and had heard the rumblings of a diesel option coming and waited and waited, we got the Tacoma and about 5-6 months later the rumors of the Wrangler diesel came true, damn. By that time we had enough experience with the Tacoma to let it go. Without the tow behind the Tacoma ran 14-19 mpg on road and about 12-13 off road. The diesel Jeep runs about 26 mpg on road with an occasional 28-29, with 19-22 off road. The extra range in remote areas is game changer, can I make to the next fuel stop or do I have to turn around? That’s mostly solved within reason of course. Sorry for the length of this, but it’s hard to express things without some background and how much I absolutely hated towing with that gas Tacoma with the damn buzzy transmission and bad mpg’s.
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