Roadtrip experience in a 392 (w/ MPG fuel economy figures)

[Left Field]

Just finished a 5100 mile / 24 day road trip and thought I'd share some of our 392 JLUR specific observations.

The route was mostly bouncing around the southwest: Depart Seattle - Orange County - Glamis - Phoenix - Prescott - Sedona - Flagstaff - Page - St. George - Zion - Valley of Fire - Death Valley - Las Vegas - Mojave NP - Joshua Tree -> Seattle.

Pretty much rookie compared to @wibornz but working up it

The trip avoided interstate except a couple short stretches of I-15 and I-40, otherwise two lane highway and around 250 miles off-road (Glamis Dunes, Schnebly Hill, Titus Canyon, Mojave Trail, Wild Horse Canyon, Macedonia Canyon, Berdoo Canyon, Old Dale Road / Brooklyn Mine Road).

Mostly stock vehicle - only a few non-performance mods so far :
- Maximus3-Rhino roof rack
- Teraflex rear hinge gate support and tire carrier
- Rock Slide Engineering 3.0 power steps

During the trip I stopped at a closed state weigh station; total weight (with occupants & gear) was 5850lbs ( 2900lbs F / 2950lbs R ).

Total fuel economy for the trip was around 15.2 mpg (measured); this was about 3-4% lower than indicated by the vehicle (approx. 15.8 mpg). Most speeds were 65-70 mph. At high elevation, no wind, 65 mph on the flat the engine would spend most of the time in 4cyl mode and get between 17-18 mpg indicated. Any other condition it was running on all 8 unless coasting. With headwinds and/or at higher speeds the gas mileage indicated would dip to 12-13 mpg. Best mileage for a tank was 17.1 mpg (measured).

Although I had a 5g steel jerry can along, fuel anxiety and range turned out to be largely a non-issue. My typical fill was between 280 & 300 miles which was around 4-5 hours driving. I still am pursuing the idea of an aux. fuel tank for the backcountry. One of our campsites was over 100 miles round trip to get more fuel. The fuel light usually came on around 18.5g out of total 21.5g capacity. Most I ever put in was just over 20g. Info page at that point indicated a range of 15 miles. Seems fair.

It was great driving a vehicle that could transition from sand, rock, snow or water fording, then pull back on the highway for an effortless merge and good highway manners. The paddle shift hill descent mode worked really well on steep rocky descents. The only anomalous behavior (not 100% sure) was easy running on some sand woops on the Mojave trail (in 4-auto), thought I heard the ABS buzzing a brake now and then. I turned off stability/traction control and never heard it again. Note taken. Most of the rest of the offroad I switched to 4-PT, figured it would save some wear on the T-case clutch pack. No lockers needed on this terrain.

Great vehicle, looking forward to the next trip!

Sponsored

 

[Noway]

Great vehicle, looking forward to the next trip!

Thank you for the hard numbers. You must be an accountant/finance/ actuarial guy. MPG is way better than a TRX @ 10 mpg in town and a lousy 12mpg on the freeway. Do you have the XR package or not? That will make a big diference imo. Do you have any pics with your 392? I'd love to see it

 

[Left Field]

Do you have the XR package or not?

Non-XR so 33's with 3.73 gears. Although 35's are in the plan

First major trip so thought I'd catch a little data. From now on the only numbers I'll probably look at will be the credit card gas pump numbers :-(

Posted a few pictures over on the Trip Journal section.

Seattle Southbound

 

[Bhodi11]

I have an XR and have done 3 trips about 3 - 5 hours away each over the last month. My oldest plays travel hockey. It’s mostly highway and I am seeing 15.1mpg pretty consistently. Around town having fun with it I get about 11.5mpg. Currently I have about 3200 miles on it

 

[guarnibl]

I was getting 16.5 on my XR on highway. Seems strange that XR highway economy might actually be slightly better than non-XR.

I have 37's (KM3) on now, so this will change obviously -- I'm guessing I'll see a 1.5 mpg drop since these are MT's instead of AT's and the weight change is substantial.

 

[son-of-odin]

First, this sounds like it was an awesome trip. Thank you for sharing because the trip itself is inspirational. Going on trips like that is one of the reasons I got mine--I want to be able to go anywhere and do anything.

Second, thank you for sharing the numbers. The first thing I thought after driving mine around for a week was WTH this is fun, but how am I going to stop at enough gas stations to keep gas in the tank, especially on a longer trip like you just did. I had some anxiety, for sure, about doing a longer trip. Your numbers are helpful, and your attention to detail was impressive (weighing at the weigh station, etc).

Did you find a "sweet spot" for freeway travel? I haven't done a trip yet longer than 50 miles, but I want to find a good speed I can travel out on the open roads knowing that I'm going fast enough (I like to go 5-10 over, and some parts of I-15 are 80 mph limit...I think going 90 would be horrible for gas mileage, but I don't know how much worse it would be) and getting decent mpg. I'm taking it for a drive (mostly south on I-15 where it is an 80 mph speed limit) next week to St. George (about 270 miles) and can report back what I experienced, but I'm wondering if you have any estimates before I go.

Thanks again.

 

[Left Field]

Did you find a "sweet spot" for freeway travel? I haven't done a trip yet longer than 50 miles, but I want to find a good speed I can travel out on the open roads knowing that I'm going fast enough (I like to go 5-10 over, and some parts of I-15 are 80 mph limit...I think going 90 would be horrible for gas mileage, but I don't know how much worse it would be) and getting decent mpg. I'm taking it for a drive (mostly south on I-15 where it is an 80 mph speed limit) next week to St. George (about 270 miles) and can report back what I experienced, but I'm wondering if you have any estimates before I go.

I played around with speed vs mpg on a long section of flat two lane at relatively low elevation (<2000'). Gas mileage dropped off pretty quickly with speed (or headwinds I found later). At 60 mph the Jeep indicated a little over 17 mpg, at 70 mph that dropped to around 15-16, and by 80 it was often 13. Even slight grades seemed to hit the mpg pretty hard but much of that probably comes back on the backside slope.

The latter number (13 mpg) was typical of what I saw on I-15. On the 2 lane I'm same thing regarding speeds, if traffic is light I'm 5-10 over. That was usually 65-70 mph. On I-15 it was usually no more than 80. It drove nice but I foolishly left the fuel page selected on the dash and the decreasing mpg numbers kept me in check.

My roof rack probably isn't helping, there is some extra wind noise from it.

LF

 

[Bocephus]

Just finished a 5100 mile / 24 day road trip and thought I'd share some of our 392 JLUR specific observations.

The route was mostly bouncing around the southwest: Depart Seattle - Orange County - Glamis - Phoenix - Prescott - Sedona - Flagstaff - Page - St. George - Zion - Valley of Fire - Death Valley - Las Vegas - Mojave NP - Joshua Tree -> Seattle.

Pretty much rookie compared to @wibornz but working up it

The trip avoided interstate except a couple short stretches of I-15 and I-40, otherwise two lane highway and around 250 miles off-road (Glamis Dunes, Schnebly Hill, Titus Canyon, Mojave Trail, Wild Horse Canyon, Macedonia Canyon, Berdoo Canyon, Old Dale Road / Brooklyn Mine Road).

Mostly stock vehicle - only a few non-performance mods so far :
- Maximus3-Rhino roof rack
- Teraflex rear hinge gate support and tire carrier
- Rock Slide Engineering 3.0 power steps

During the trip I stopped at a closed state weigh station; total weight (with occupants & gear) was 5850lbs ( 2900lbs F / 2950lbs R ).

Total fuel economy for the trip was around 15.2 mpg (measured); this was about 3-4% lower than indicated by the vehicle (approx. 15.8 mpg). Most speeds were 65-70 mph. At high elevation, no wind, 65 mph on the flat the engine would spend most of the time in 4cyl mode and get between 17-18 mpg indicated. Any other condition it was running on all 8 unless coasting. With headwinds and/or at higher speeds the gas mileage indicated would dip to 12-13 mpg. Best mileage for a tank was 17.1 mpg (measured).

Although I had a 5g steel jerry can along, fuel anxiety and range turned out to be largely a non-issue. My typical fill was between 280 & 300 miles which was around 4-5 hours driving. I still am pursuing the idea of an aux. fuel tank for the backcountry. One of our campsites was over 100 miles round trip to get more fuel. The fuel light usually came on around 18.5g out of total 21.5g capacity. Most I ever put in was just over 20g. Info page at that point indicated a range of 15 miles. Seems fair.

It was great driving a vehicle that could transition from sand, rock, snow or water fording, then pull back on the highway for an effortless merge and good highway manners. The paddle shift hill descent mode worked really well on steep rocky descents. The only anomalous behavior (not 100% sure) was easy running on some sand woops on the Mojave trail (in 4-auto), thought I heard the ABS buzzing a brake now and then. I turned off stability/traction control and never heard it again. Note taken. Most of the rest of the offroad I switched to 4-PT, figured it would save some wear on the T-case clutch pack. No lockers needed on this terrain.

Great vehicle, looking forward to the next trip!

Great info, thanks! How did you tote your Jerry can?

 

[alksion]

From what I’ve heard, no aux tank is coming to the 392.

 

[son-of-odin]

I got ~17 mpg on a drive where I took the freeway through Salt Lake (went 75-80 mph), got onto I-84 to go up the canyon towards Mountain Green, then went over Trapper's Loop into Huntsville (and made the return trip the other direction). There are lots of ups and downs here; Trapper's Loop is a 55 mph zone, but I went just over 60 both up and down. I hate to say it, but considering I have the 392 with the XR package (no mods), I was/am pleasantly surprised. After this trip, I drove south on I-15 to St. George where the speed limit is 80, and there was a noticeable drop in efficiency when going 80-85 mph. I averaged closer to 16 mpg on that trip.

With gas prices the way they are, my adult brain says to slow things down a bit...but my child brain says it's too much fun when I get to drive faster. I'll pay the price for being childish, I guess.

Sponsored