1100 mile road trip 19 MPG average

[Keith Gover]

I'm old school and also an engineer, I kept my data in a spreadsheet:

 

[Winston]

Yeah, you 19'ers must be going downhill with a tailwind with a 3.6 Pentastar.

 

[srj67]

For what its worth the sweet spot of the 392 where it gets its best mileage is 2000 to 2100 rpm. And if your running slow enough the engine will kick into the 4 cylinder mode and get even better fuel economy.

Keeping it in this range can be hard considering the stock gearing and the full assortment of tire sizes you can have on the platform. On the older 392's with the small tires, 3:73 gearing and lower profile and less aerodynamic drag made this easier.

I look at it this way if I wanted great fuel economy I would have bought a Prius, lol.

 

[TuffyMan]

This is city driving taking it easy.

 

[Winston]

View attachment 50200This is city driving taking it easy.

Multiply it by 392 and you get your smiles per gallon, which is the universally accepted unit of measurement for this vehicle.

 

[srj67]

Not as good as last year- but still managed to get over 19 from Little Rock to Colorado.

 

[OldVetteGuy]

Im just wondering if his jeep's MDS is maybe stuck in the 4cyl mode all the time, lol, just having fun!

 

[srj67]

The funny thing is I owned a 4xe for about 8 months before Jeep got it back under the lemon law and I came back to my senses and bought a pushrod V8. On the same trip the 4Xe only got into the mid 18s. Makes sense on one hand as you’re not hauling a battery around, but I was still surprised. And I had the stock 33s on the 4xe, I’ve got E rated 35” Nittos on the 392. Around town is a completely different story, but the 392 beats a 4xe on a freeway road trip.

 

[Captain Overkill]

Ha ha… it’s ok if you don’t believe me. Hold my beer!

With a 1,100 miles trip and almost 98 hours of driving, that's only a little over 11 mph average speed. Something is not adding up.

 

[station378]

That’s solid mileage for that route, especially with 37s. The steady highway speeds probably helped a ton, and Black Bear doesn’t really rack up enough miles to drag the average down much. I’ve seen similar on long, consistent stretches where the wind is calm and elevation changes work in your favor. Once you get back to mixed driving or stop and go, it usually settles back into the mid-teens. Sounds like your setup is dialed in.

 

[chrisazm]

That’s solid mileage for that route, especially with 37s. The steady highway speeds probably helped a ton, and Black Bear doesn’t really rack up enough miles to drag the average down much. I’ve seen similar on long, consistent stretches where the wind is calm and elevation changes work in your favor. Once you get back to mixed driving or stop and go, it usually settles back into the mid-teens. Sounds like your setup is dialed in.

It definitely helped that my route back was on the reservation roads. A lot of 60 mph and mostly flat.

 

[@JC]

Still beating this dead horse I see huh

 

[3TV]

I posted earlier in this thread about the time I got 19 mpg in my 392. Recently, I was able to top that.

Just last weekend I took our 392 4-wheeling with a friend. I fueled up at home in Cedar City, UT the way I usually do. The pump will click off, then I put more fuel in until it clicks off again, so I know it is as full as it can be. Then I drove over Cedar Mountain on Hwy 14 to Hwy 89, and south to Mt. Carmel Jct, where I repeated the same refueling process to make sure the tank was full before leaving the highway to go 4-wheeling. Hwy 14 starts at 5,700 ft elevation, crosses a 10,000 ft elevation mountain pass, and drops back down to 5,900 ft elevation. It is a winding mountain highway with turns at 25 mph and brief straights at 55 mph, but more turns that straights. Once on Hwy 89 the speed limit is 65 mph, but there are numerous turns you need to slow down for and 3 small towns you have to slow down for as you drive through them. It took 2.72 gallons to go 63.9 miles, for a hand calculated gas mileage of 23.6 mpg. I had made sure the gas tank was as full as I could get it both times. The figures are accurate.

How in the world did a 392 on 40s get 23 mpg? My only explanation is that it climbs the uphill grades so effortlessly that it does not need hardly any extra throttle application on the uphill's. It doesn't need to downshift and rev the engine; it just drives normally. But on the downhills, it changes to 4-cylinder mode and just coast along. At least half the trip was in 4-cylinder mode.

I'm ok if you guys don't believe me on this, LOL. I almost don't believe myself. But these are the numbers I got, and I really tried to make sure they were accurate.

 

[YGBSM]

I was going to brag about almost 15 MPG on a short trip.

 

[392... The Bronco Killer]

The most I have ever gotten was 14mpg on stock 35's and that was taking it easy. Normally I drive like a maniac!

 

[Maui73]

My arizona to utah trip I got 19 mpg on the full tank of gas. My Jeep is factory stock. Jeep was loaded approximately the weight of four people.

 

[Ced392]

wow 19 mpg is amazing. Best I ever get is 16 mpg but then again I haven't driven more than 100 miles of highway. City driving and cold starts really kill the MPG.