Jeep 392 MPG / Gas Mileage thread

[BenLandry]

We had a customer who inquired with 37'tires and was getting 4.7 MPG. Can not buy this rig for the fuel economy

I have 37x13.5 on 20s…I drive it like a race car and I’m getting 11mpg after 6500 miles. I do see 8th gear even at 85 mph but it is pretty quick to down shift with any little change. I have 4:56 gears waiting at the shop to get installed. I’ll report back after some time with them but install might be another month away.

 

[Ward]

You don't buy the Jeep 392 for gas mileage, but I'm a curious as to what everyone seems to be averaging? TFL posted a video showing 18.8mpg over 250 miles. That's impressive!

I have 3050 miles and avg 19 hwy and 15.5 city

 

[Jeepstin392]

It’s close to my GC SRT.
currently at 483 miles on the odometer.
Around town, I average 13.2-13.5
highway, I’ve been resetting and cruise the toll road (no traffic) and getting 16.8 average. Same when on cruise control.

Its better than my JKU was. I got 13 everywhere I went.
Dodge Ram? 10
my Land Rover? 12 at best.

 

[Leslumpy]

My XR392 with 13-14mpg from the computer with what the dealership first tank, just filled with 93 with 10% ethanol and doubtful it’s winter blend yet… which is good for 1-2 mpg more. This is mix of city and 70mph highway.

 

[byhumba]

This is in a flat section of my trip. I have the original 33s and original gears (non-Xtreme Recon). Seems to be in the 1,800 RPM vicinity and about 50 miles after resetting the MPG, I was getting 20 MPG. Ended my 80 mile trip at 20.5 MPG. I used adaptive cruise control all the way at 70MPH and ignored the temptation to open it up a few times. Lol. Two areas of about 5 miles each with slow moving traffic.

 

[Jeepstin392]

This is in a flat section of my trip. I have the original 33s and original gears (non-Xtreme Recon). Seems to be in the 1,800 RPM vicinity and about 50 miles after resetting the MPG, I was getting 20 MPG. Ended my 80 mile trip at 20.5 MPG. I used adaptive cruise control all the way at 70MPH and ignored the temptation to open it up a few times. Lol. Two areas of about 5 miles each with slow moving traffic.View attachment 1961

I suspect that about as good as it will get. My GC SRT, best ever was 23.5, without running economy mode, similar numbers to what you’ve posted. Cruise set at 75, relatively flat (rolling hills, no mountains). More aerodynamic though.
For a brick with a 6.4P, 20 is decent on the highway.
Around town (Denver metro and foothills) I’m getting 14.4-14.8 avg., and just driving “normal”.

 

[byhumba]

I suspect that about as good as it will get. My GC SRT, best ever was 23.5, without running economy mode, similar numbers to what you’ve posted. Cruise set at 75, relatively flat (rolling hills, no mountains). More aerodynamic though.
For a brick with a 6.4P, 20 is decent on the highway.
Around town (Denver metro and foothills) I’m getting 14.4-14.8 avg., and just driving “normal”.

Yeah, I'm getting about the same as you, 14 to 15 mpg around town.

 

[Gnomad]

I’m not sure if anyone has posted this in the thread, but if you’ve moved to bigger tires and not recalibrated for them, your mpg readings will come out lower than actual. Just throwing that out there.

 

[kbernard]

I was at 19 on the hwy with stock tire and wheel and now with 37's about 15-16 mpg. On another not playing with the exhaust it gets 1 mpg better without the performance exhaust on.

 

[Jeepstin392]

I’m not sure if anyone has posted this in the thread, but if you’ve moved to bigger tires and not recalibrated for them, your mpg readings will come out lower than actual. Just throwing that out there.

I’m not sure if anyone has posted this in the thread, but if you’ve moved to bigger tires and not recalibrated for them, your mpg readings will come out lower than actual. Just throwing that out there.

I’m calibrated
Tazer JL Mini
It’s pretty bad ass.

 

[JeepnJam]

Computer tells me I am getting 13 - 13.5 mpg around town. If I go 70 on Interstate I can get 15 mpg. I’m on 37x12.50s and have calibrated the speedo. Stock gearing

My gladiator on 38x13.50s was getting 15mpg around town and 17mpg at 70 on interstate. It was calibrated as well. Stock gearing.

 

[JeepnJam]

I was at 19 on the hwy with stock tire and wheel and now with 37's about 15-16 mpg. On another not playing with the exhaust it gets 1 mpg better without the performance exhaust on.

Do you think it gets better mpg with the performance exhaust turned off because you’re not launching to hear the motor as much?

I quit trying to micro mpg out of my 392 because every time I get it up to 14.5mpg my wife takes it somewhere and brings it back at 12.5mpg - no idea how that happens…lol.

 

[kbernard]

Y

Do you think it gets better mpg with the performance exhaust turned off because you’re not launching to hear the motor as much?

I quit trying to micro mpg out of my 392 because every time I get it up to 14.5mpg my wife takes it somewhere and brings it back at 12.5mpg - no idea how that happens…lol.

Yes with the performance on you loose 1 mpg. I don’t care personally but just thought it would be the opposite, as well just playing around with it

 

[JeepnJam]

Y

Yes with the performance on you loose 1 mpg. I don’t care personally but just thought it would be the opposite, as well just playing around with it

What psi are you running in your tires?

 

[Tree]

This is my average (via Computer) and I have 37’s with a 3.5” lift…
This was my first tank with 93 octane.
It’s 14.6 today hand calculated.

 

[Yaak392]

Has anyone driven the 392 Rubicon long distance and get MPG similar to what TFL (video) got?

We're close to 5000 miles. Today we made a 3 state road trip. Avg was 18.6 (for around 400 miles)

 

[rhammer94]

I was at 19 on the hwy with stock tire and wheel and now with 37's about 15-16 mpg. On another not playing with the exhaust it gets 1 mpg better without the performance exhaust on.

I'm going to try this out we'll see, I'm at 14mpg stock city now.

 

[Yaak392]

The break-in calls for full range of the RPMs during the 300 to 500 mile (use paddle shifters) phase. That was a lot of fun. I even red lined it a few times. Lol.

6000 rpm sounds scary.....
I'd be skeerd I'd break something. Lol
But it's hard to keep my foot off the pedal too....

 

[byhumba]

6000 rpm sounds scary.....
I'd be skeerd I'd break something. Lol
But it's hard to keep my foot off the pedal too....

My 392 is performing great. These engines are designed to take a lot of abuse. I only did it, but never sustained red line, during that 300 to 500 mile window. You don't have to reach 6,000 RPMs if you don't want to, the manual just asks for full range of the RPMs without being specific.

 

[Yaak392]

My 392 is performing great. These engines are designed to take a lot of abuse. I only did it, but never sustained red line, during that 300 to 500 mile window. You don't have to reach 6,000 RPMs if you don't want to, the manual just asks for full range of the RPMs without being specific.

I don't think I have hit red line yet. I was trying to be humorous. I'm sitting in the dark ( power outage due to high winds last night. Operating on our solar panel powered battery backup.) Watching a buck chase a doe. (RUT) And a couple of young cow elk showed up this morning. Life is good.