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Hypermiling the Diesel JGC: Max Range, 700, 800, 900 Miles?

15K views 77 replies 36 participants last post by  penst8grad 
#1 ·
Has anyone on JeepGarage gotten 700+ miles on a tankful? Or even 800 or 900? Theoretically it's possible. The tank size is 24.6 gallons. If we nominally use 23 gallons then these are the possible distances we can go on a tankful:

460 miles @ 20mpg
575 miles @ 25mpg
690 miles @ 30mpg
805 miles @ 35mpg
920 miles @ 40mpg

I am planning a trip and may see how far I can go on a tankful. I think I can get 800+ miles. Trouble is, at only 50 or 60 MPH it takes FOREVER to get anywhere. The real test will be on my patience!

Hypermiling - who's done it and how far have you actually gone? Who has hypermiled their WK2 CRD? Other CRD owners (non-WK2), your results are also welcome but be sure to mention what Jeep you drive.
 
#3 ·
Obviously, speed kills here. If you could find a 45mph road you could probably run it 900 miles. Also, I think a stripped down 2wd limited would be the lightest model with the most potential for extreme mpg.

Also, temperature could play a role. I don't think triple digit temps are conducive to hypermiling.
 
#7 ·
Meh, I typically get 8.5 L/100 km in the summer on #2 while driving under the speed limit on flat midwestern interstates. Winter driving in the EcoDiesel becomes amazing, especially around town... I get 16 to 14 L/100 km usually, provided I don't drive too aggressively and coast when I can. Driving the same patch of interstate during the winter at the same speed as the summer will net me 13 to 12 L/100 km on winter blend. Worse if it's really shitty weather, of course.

YMMV (haha).
 
#8 ·
I've seen a few tanks of hand calculated 34mpg for summer driving.

My winter mileage hand calculated was at it's worst 26mpg with driving in freezing temps with heavy snow.
 
#10 ·
I recently noticed over the last 2000 miles that my miles per gallon have stepped up a couple miles per gallon. I think now at 28K miles that is do to the engine being fully broken in. At 80 mph I have gone to getting 29 mpg without a strong headwind.'

I owned a Super Duty before this and the mileage jumped up but not until I had close to 60K miles on that 7.3L engine.

Curious to see if others have noted the change in mpg based on engine break in...
 
#20 · (Edited)
Am bumping this because at 0330 in the morning, we (4 adults) will leave on a 1,000 mile round trip to Oceanside / Camp Pendleton in my 2016 JGC CRD. I will do some MPG checks at different speeds using the JGC's computer, and an overall MPG check at the end of the trip, calc'd by hand.

My rig has 13K miles on it, so it's still new. I'll see what I get and report back here.
 
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#22 ·
Best I have done was a hand calculated 30.0 MPG from Raleigh NC to Huntsville AL, through the mountains. Gassed up after 650 miles, but had another 2+ gallons in the tank so could have hit 700 easily. Also, this was with ~2k miles on the odometer.
 
#23 ·
My best so far was 30.55 mpg hand calc over 397 miles. A lot of 50 to 70 mph highway driving. That was at 13166 miles on the odo. Now 19800 miles on the odo.
 
#24 · (Edited)
The best fuel economy I have hit in my '15 4x4 with heavy Skid Plates and driver only is 31.5 MPG driving across Oregon and Idaho on 2 lane when I picked the Jeep up brand new in Bend, Ore and drove it home to Montana. All of that trip was 65 MPH or lower. The most miles I have hit in a tank is 719 miles and that is loaded with family and gear - that trip avg'd 29.9 MPG. I only have 7,000 miles on the odometer so she isnt broken in yet. Midnight (Jeep Grand Cherokee) | Fuelly
 
#25 ·
I don't know how you all get 30+ mpg. Even when my Summit goes into Aero mode, the best I've ever gotten is 28 mpg. Normal highway running (75-80) it's generally in the 25-27 range. The only way I'd get 30 is if I set the cruise at 65 in a 65 zone, but I'd get run over by every 18 wheeler on the highway. Of course I'm stuck with B20 here in the people's republic of Illinois. Only times I've run B5 for any extended road trip I've got the 7,000 race hauler behind me.
 
#26 ·
Typing this from our hotel room in San Clemente. With 5 adults in the car, and all our luggage, we made it 500 miles on the first tank. We finally filled the tank last night in Oceanside. Our guests were wondering if we were ever going to gas up!

On Sunday morning when we left at 0330, it was nice not having to stop to get gass. Most in the car were asleep, so I kept driving south until just before the Grapevine when they woke up, and then we stopped for breakfast.

It is nice stopping when you want to, instead of when you have to because the gas tank is already empty.

I will tally the MPG figures after driving home tomorrow.
 
#31 ·
I used to get 31 - 32 on the highway but noticed it has dropped to 25-27. I have 30,000 on mine. I took it to the dealer and was told that I need to have the fuel filter changed every 10,000 miles, and i should be adding a additive to my fuel. One for winter months and one for summer. They also told me I should be hooking up my engine block heater every time the temp drops below 60. I've had my 2014 almost 3 years now and never done any of this. thoughts?
 
#32 ·
Change dealer... And when you walk out the door on this one give them a curtesy copy of the JGC diesel supplement manual. I wouldn't let a dealer that never even read the user manuals touch my ride with a 10 foot pole.

Without hijacking the thread too much, fuel filters should be changed every 30K (20K with BioDiesel) and block heater is recommended below -10F and required below -20F. Additives are optional. Many folks here will use a lubricity additive to protect the HPFP that is known to have lubricity starvation catastrophic results.
 
#35 ·
My list of fuel economy killers on a flat interstate:
1) Those damn headwinds that always seem to follow me no matter which way I'm going
2) Winter blend / biodiesel
3) Below-freezing temperatures or extremely high ambient temps
4) Speeding

Cargo & towing are also going to drag economy down.

Economy boosters:
1) Those blessed (but rare) 40+ km/h tailwinds
2) ACC drafting tractor-trailers (though this upsets some truckers)
3) High tire pressure (be careful if you do this in the winter, as it affects braking)
4) "Goldilocks" ambient temperature (my unscientific estimate of this is ~22 °C)
5) Transmission at operating temperature

...and, of course, many on the forum use a GDE tune.

One thing that *doesn't* appreciably help is "premium diesel" (i.e. putatively higher cetane). I've tried multiple varieties, and if I ever got a boost it was a secondary or tertiary effect and therefore never showed up in my caculated logs.
 
#36 ·
My list of fuel economy killers on a flat interstate:
...
4) Speeding
That is my biggest challenge. From the days when my motorcycle was my only vehicle, I rode a little faster than traffic. This kept the action in front of me and I didn't have to worry so much about what was behind me. Cars were essentially pylons to slalom around, and my mirrors were mainly to look for highway patrol. I did get the occasional speeding ticket.

Even in the JGC I feel like I'm not making good progress unless I'm passing people along the way. I am trying to recalibrate my brain housing group for that.
 
#37 · (Edited)
Here's my rule of thumb to get great fuel mileage on the highway...never run more than 5mph over the posted speed limit, never exceed 70mph, always keep the tires aired up to 36psi, use cruise control as much as possible and always try to keep the vehicle in Aero mode. Stay off the brakes...look down the road leave off the "skinny pedal" and coast to a stop if possible and use the brakes as little as possible. When going to California from the east coast the best I have got was 31.5 MPG hand calculated. Another thing you wont get your best mileage until after 10,000 miles on the clock. Here's a pic from that trip.
 

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#38 ·
Got my 2016 JGC Limited at the start of Sept, just turned 5,200 miles. I live in Northern Virginia and have made 3 trips down to Raleigh, NC and back. So far I'm getting around 30.5 MPG on those long distance runs and about 25 mpg around town.
I've got some experience hyper miling cars and used to love to borrowing my friend's trucks and returning them with the highest MPG numbers they had ever seen.
So far it's been an education in changing my driving style. I think this is one of the biggest and hardest things to learn/break yourself of VS driving a gas car. You have to keep the RPMs down, keep your foot out of the accelerator (when safe to do so), accelerate slowly, and learn to coast.
I'm one of those guys who puts the car in neutral during extended stretches vs engine braking. This is one of those philosophical "tastes great/less filling" debates where one camp wants more MPG and the other argues the safety issue if you suddenly needed to accelerate to veer out of danger and found yourself in neutral.
I definitely second the advice that's been given already and will add some of my own:
Accelerate slowly
brake as little as possible
coast when capable
65mph seems to be the sweet spot for speed and still maintaining good MPG
Tire pressure is key, but folks who overinflate just sacrifice tire life for MPG and that's not smart either
never do any of this if it will negatively impact your safety or the safety of others on the road.

Looking forward to learning from the rest of the community about this great ride!
 
#39 ·
...
I'm one of those guys who puts the car in neutral during extended stretches vs engine braking. ...
I used to do this, too, but learned that the fuel cutoffs in modern vehicles save more fuel than idling in neutral. Coast in gear, unless you're driving an old carburated vehicle. There are a few exceptions, but they're older vehicles (pre-2006?).

I think you'll find that the torque converter (when unlocked) in your Ecodiesel provides so little resistance that coasting in gear is virtually identical to coasting in neutral in terms of resistance to forward motion. Coasting to a stop requires blocks of planning in advance. ;)
 
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#40 · (Edited)
I like the CRD's fuel economy. But the problem I have with getting 30+ mpg is time. The longest I ever drove on one tank was 835 miles, but if I drove that at 75+ mph it would take over 4 hours less time - approximately ...

15 hours at 55 mph
10 hours 30 minutes at 80 mph

Put another way, driving 55 costs about 40% as a time penalty. Significant. Especially since the CRD cruises effortlessly at 80, 90 mph.

BTW, the cruise control won't set at over 100 mph. It'll set at 100, but not at 101.
 
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