3.6 Trash MPG

[Old Jeeper]

That's exactly what I get, BF K02 34.4, crappy 3.45 gearing, 4 door, metal bumpers, V6

I would think your 3:45 gears would outpace my 4:88s in mpg. That said this is not always the case when you go taller tires on lower (numerically) gears. This is because of the torque multiplier effect which has now decreased as a result it takes more effort of the engine to turn the bigger tires.

MPG is hard to nail down.

Hand Calculated MPG is a MYTH. THe ONLY way to get accuracy in hand jammed it to fill the tank to the LIP of the filler spout. But it take a long time to do so. Most only fill till the hose clicks off. Nothing is more inaccurate than that. If you fill to the lip and stop, well just wait and you see your fuel go back down.

As for the so-called 'Lie O meter'. Is it accurate? YES! Its accurate due to consistency.

I have compared filling to the lip vs the lie o meter on Jeeps and my Ford Super duty trucks. The difference is: +/- 0.1. Basis: 6 Superduty trucks, JKRR, JLR, 2 x JT Rs

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[Joaquim]

I would think your 3:45 gears would outpace my 4:88s in mpg. That said this is not always the case when you go taller tires on lower (numerically) gears. This is because of the torque multiplier effect which has now decreased as a result it takes more effort of the engine to turn the bigger tires.

MPG is hard to nail down.

Hand Calculated MPG is a MYTH. THe ONLY way to get accuracy in hand jammed it to fill the tank to the LIP of the filler spout. But it take a long time to do so. Most only fill till the hose clicks off. Nothing is more inaccurate than that. If you fill to the lip and stop, well just wait and you see your fuel go back down.

As for the so-called 'Lie O meter'. Is it accurate? YES! Its accurate due to consistency.

I have compared filling to the lip vs the lie o meter on Jeeps and my Ford Super duty trucks. The difference is: +/- 0.1. Basis: 6 Superduty trucks, JKRR, JLR, 2 x JT Rs

From what I've noticed, with the 3.45 gearing, stop/start city driving is horrendous. Highway I can get 18/19 even 20 MPG

 

[Old Jeeper]

From what I've noticed, with the 3.45 gearing, stop/start city driving is horrendous. Highway I can get 18/19 even 20 MPG

YES, your mpg can improve with the V6 as its torque curves is higher in the rpm band. Drive faster and you can see better mpg. My mpg at 70 mph gives me an overall 16.x-17.x, but in town mid 14s-15s.

 

[AFD]

Hand Calculated MPG is a MYTH. THe ONLY way to get accuracy in hand jammed it to fill the tank to the LIP of the filler spout. But it take a long time to do so. Most only fill till the hose clicks off. Nothing is more inaccurate than that. If you fill to the lip and stop, well just wait and you see your fuel go back down.

Always use the exact same pump at the exact same filling station 99% of the time (usually at the same avg temp and time of day when possible) and it seemed super consistent without overfilling. Just stick the nozzle all the way in at the same depth every time. Stop when it clicks off once. Did this for my last car and kept detailed records, and fuel mileage was insanely close between fill-ups (if keeping the same daily route and driving patterns).

The gas pumps in my state are regularly inspected for calibration by the Dept. of Weights and Measures, so there shouldn't be much discrepancy there either.

 

[Old Jeeper]

Always use the exact same pump at the exact same filling station 99% of the time (usually at the same avg temp and time of day when possible) and it seemed super consistent without overfilling. Just stick the nozzle all the way in at the same depth every time. Stop when it clicks off once. Did this for my last car and kept detailed records, and fuel mileage was insanely close between fill-ups (if keeping the same daily route and driving patterns).

The gas pumps in my state are regularly inspected for calibration by the Dept. of Weights and Measures, so there shouldn't be much discrepancy there either.

Remember this: When you use the stop click method the question is when did they replace the hand nozzle? They do replace them on a fairly regular basis when they wear out, which is more often than one may think (I used to own a Exxon Station).

If you fill to the lip each time then it makes no difference what station or pump. I travel to much to use the same station...

 

[AFD]

Remember this: When you use the stop click method the question is when did they replace the hand nozzle? They do replace them on a fairly regular basis when they wear out, which is more often than one may think (I used to own a Exxon Station).

If you fill to the lip each time then it makes no difference what station or pump. I travel to much to use the same station...

Yeah, my regular pump was recently changed after another company took new ownership of the station. Happened right after I got my JL and sold my last car, so not really sure how much of a difference it made. Probably a fair bit, since the new rubber nozzle hoods were noticeably longer with <1" less of insertion.

I'd fill to the lip, but I get bothered enough just resting my gas cap on the fender. Would hate to see the mess I'd make topping it off like that ?

Same pump with one click is probably "close enough" for my own needs, which is mostly just curiosity and as a warning if something with the vehicle isn't working as usual.

 

[azjl#3]

28000 miles on stock 18 jl ur. Getting all the way down to 11mpg in town short drives. 19-20 highway, in mountains no less, doing 65 up and down. I got 18 on interstate 10 level for 900 miles. Doing 65-70.

It's all about warming up axle fluids. That and AC. Start stop supposedly gives you 1mpg in town. I never use it.

35 tires kill milage, what brand? Some are 100lbs per and rotational mass starting and stopping kills mileage

 

[Yawnie'sPapa]

The 3.6 does not get great gas mileage if you drive with any kind of urgency, well, i have yet to get any real good gas mileage, lmfao! Just be happy you dont have the extra weight of a gladiator. I have a heavy foot, but its a serious struggle to average over 16 mpg for me unless im on a turnpike or something and just sunday driving it.

My 3.6 JT got 22 stock. It's now in the 18-19 range due to the crazy extra weight of steel bumper, winch, 2" front receiver, snow plow brackets and mounting bar and another 150 or so pounds of power steps, plus A/T tires vs. the H/T it came with. 22 was easy at 45-55 (up to 60) mph.

My daily driving is 30mph or less for maybe a combined 3 miles

That's the type of Jeep I'd not want to buy if you sell it later. That's killer on gas engines! Horrible, I hope you change oil very frequently! Acids form, things go really bad. It never gets hot enough to burn the water out of things. Sorry, but that's engine killer - and battery killer unless you use a tender on the batteries daily.
You can't possibly keep the batteries topped off otherwise. That speed, that short drive - bad for everything from engine to batteries, and more.

And like already said way back - why are you even looking at the mpg readout without changing the tire sizes in the system. It can't be accurate because it thinks you are driving a different distance and can't be accurate.

As a side note - once I set my JT up for my different tires, it's been anywhere from right on, to maybe off .4 or .5 mpg. I track it with FillUp and it usually matches the cluster display. I have found that if it's high one time, it's low the next time, and over several tanks, the numbers all but match. So these can be accurate - but garbage in, garbage out. And you can never fill a fuel tank to the exact same level two times. Can't do it. You think you are, but unless you park in the exact same place at the same pump and measure how far down the fuel level is when you stop, not to mention ambient temperatures and the temperature of the fuel..... it's going to be different.
That's why you can't go by a single fill - you have to average several - if using an app or hand calculations.

 

[FRV]

21 JLUR. 3.6. Manual trans. Plastic bumpers. 2.5 AEV dual sport lift. Stock 33s. Ursa Minor camper top. Warn Zeon 10s. Long range America 17 gallon aux fuel tank. 26,000 miles. I grew up drag racing but I accelerate like an old lady now and am conscious of fuel consumption. I know all the MPG tricks.

At 65 on rolling interstate we average 18-19.5 mpg. Lightly loaded. Fully loaded with all kinds of equipment and camping gear we are still close to that average maybe lose about 1 to .5 mpg.

35s and up are a killer to mpg. Without calculating for larger tires you are wasting your time even thinking about mpg. The fuel metering is all based on electronic sensor computations.

I doubt you have a mpg lemon. You have to set yourself up for success though.

I have been told by AEV and techs at LRA to never force fuel into the tank. The owner's manual says the same thing. Fuel can be pushed into the evap system and screw up the sensors. When the fuel pump shuts off on high flow I give it 10-15 seconds to settle and half flow one more time and that's it.

I agree with other who have said fuel has to be calculated over several tanks In similar terrain and speed. But I have found the dash calculator close on my Jeep.

 

[LOBBS]

Hey guys - it's been a while but I am finally back in a JLUR and I'm having some issues with absolute trash fuel economy. My daily driving is 30mph or less for maybe a combined 3 miles so I'm not expecting anything great. Currently sitting around 13mpg (was around 10 with leaving it running during the winter). Did a roadtrip to my house up in Maine a few weeks ago, and the Lie-o-meter was 14.6 on the way (but there was a 30mph cross/headwind) and on the way home I squeaked out 15.6mpg. On the trip up, I went through 3/4 of a full tank of 87. Cruise control was set at 70 (which is actually 73) the whole time on the interstate, and up north was 10min trips at 35-55. Transmission had no problems hitting 8th and really never had to drop below 7th except for the occasional monster hill. The only thing to mention (mods below) is I have not adjusted my speedo for the tire height (but I've done the math).

2020 JLUR Hard Top
44k miles
3.6 Pentastar w/8spd
35" Duratracs @ 37PSI
PSC Bruiser Stubby with Warn Zeon 8-S
Factory rear steel bumper
No lift. No engine mods.

If you've not adjusted your speedo not only is your speed reading off but also the number of miles that it's counting on your odometer.

 

[J.Ferreira]

I would think your 3:45 gears would outpace my 4:88s in mpg. That said this is not always the case when you go taller tires on lower (numerically) gears. This is because of the torque multiplier effect which has now decreased as a result it takes more effort of the engine to turn the bigger tires.

MPG is hard to nail down.

Hand Calculated MPG is a MYTH. THe ONLY way to get accuracy in hand jammed it to fill the tank to the LIP of the filler spout. But it take a long time to do so. Most only fill till the hose clicks off. Nothing is more inaccurate than that. If you fill to the lip and stop, well just wait and you see your fuel go back down.

As for the so-called 'Lie O meter'. Is it accurate? YES! Its accurate due to consistency.

I have compared filling to the lip vs the lie o meter on Jeeps and my Ford Super duty trucks. The difference is: +/- 0.1. Basis: 6 Superduty trucks, JKRR, JLR, 2 x JT Rs

I go till the click, wait about 15 seconds, and go till it clicks again.
I haven't reset the lifetime average since I bought it and it's sitting at about 21.6, and my fuelly tracker is like 21.5. I'd say I fill fairly consistently. I primarily go to one gas station so the pump handles are the same and the vapor lock is pretty consistent across the ones that I've used.

 

[TheRaven]

It's all about knock potential. Any knock (whatsoever) is in some way detrimental to your piston rings and cylinder surfaces. The Engine Control Module (ECM) will certainly 'react' to knock events and retard timing but only after-the-fact. Some damage has already been done.

No. This is hyperbole. The very definition of "modern engine control" is: advance timing until knock is detected, then pull back timing, and repeat. The ECM does this continuously all the time. Every single electronically controlled engine, no matter the grade of fuel, knocks, a lot. If the ECM is doing its job, you will very rarely hear it. If you hear it frequently, something is wrong with either the ECM or the fuel you are using. This has been discussed at length repeatedly and the answer remains the same - both the 3.6 and 2.0 should present little to no audible knock running on regular fuel. If audible, chronic knock is heard, there is a problem with the motor or the fuel quality.

 

[GrayWolf.Overland]

3.6 ESS - and yes I use the ESS to its full extent in city driving
4.56 Gears, 1.5" Clayton Lift
BFG KO2 35s (315/70/17 C)

I get 16.5 mpg average around town - I live in a very hilly area with a lot of uphill climbs that can't be done under 2800rpm :|

On highways with relatively flat to medium roads here I rack up about 19.5-20mpg.

I drive very conservatively and use the engine sound as my mental meter when driving. The 4.56 gears allows the Jeep to shift down earlier and keeps the rpms optimal for 35s

 

[jellis4148]

I have found that if you can keep your tach under 2,000 rpm when driving you will get your best mpg. I can get 20 out of my Wrangler. It has 37 inch beadlocks that weigh 115 pounds each running stock gears.

 

[crux360a]

I do casual highway driving however most of my drive is to and from work which is a 2.3 miles grocery store ECT.. and just out enjoying the weather on a beautiful day.. I get absolute shit MPG (I'm getting if im lucky 11.2 MPG), I did change speedometer to reflex the correct size tires.. So i guess my questions is what brand of Ring & pinion did you all go with? And has any of you gone up to a 5:13?

2022 unlimited Rubicon
37 SST PRO
4,057 Miles on
Picture is what I’ve done to her

PS ( No I don't drive like a bat out of hell)

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