First long trip review + gas mileage/gas tank rant

[Oil_Burner]

Besides the engine breaking in, I can think of 2 additional factors.

Fuel and tires. The winter blend of 87 octane likely has 10% alcohol. The summer blend may have none, depending on where you get it in the USA. I can easily see a 10 MPG difference between the two fuels between summer and winter in my Prius. New tires also cut down on mileage since they are more spongy and flexible. As the tires wear, you mileage will improve.

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[Gatorac]

Sport S with 33" tires (I have recalibrated with JScan), I was getting 15.6 on the interstate. 75mph average speed. Good news is it only dropped to 13.3 when I was towing.....

 

[htremper]

I'm not expecting much more than 20mpg if that with the aerodynamics of a brick wall along with a curb weight of over 2 tons. The Wrangler wasn't any better with only 5 speeds in the auto and even wrose aerodynamics, I think, than the Gladiator. There are enough tests showing a truck bed having little to do with efficiency with or without a tonneau as the pocket of air inside the bed doesn't move much while in motion and the air just flows over it out the back.

The video as I recalled, even drove with the tail gate up and down as there is also bro science saying leaving the tail gate down will let air flow out of it.

Ha...stealing Bro Science

I noticed a pretty significant drop in mph when I have bikes on the back (hitch rack) then not...which is understandable, but its even more then my RTT which is above the roofline...I am guessing that's why a lot of trucks have those flaps at the back of their trailer

I am sure someone here can explain aerodynamics here better...

 

[smlobx]

Just came back from a short trip of about 300 miles and got right at 18.0 mpg according to the trip odometer with my stock Rubicon with an Alu-Cab canopy on back. Overall with about 11K miles on it so far I’m averaging between 17.5 and 18 mpg depending on the drive.

A couple of comments that many already know. Driving above 70 mph and the mileage really starts to suck. If I remember correctly from last summer the interstate speeds in northern Tejas is 75 and the traffic was going about 80+. Add that to the ever present winds and I would not be surprised to see 15 mph on a trip like that.

The gas tank is another issue.. NO ONE and I mean absolutely no one has ever put close to 22 gallons in their truck when filling up. As far as I can figure either FCA lied and installed a 20? Gallon tank or (more probably) the software is so conservative that even when it shows 10 miles left in the tank you actually have 2 or 3 gallons left. Either way I don’t like it and will be installing a Long Range America additional fuel tank under my Gladiator in a couple of weeks to give me the range that should have come with this truck...

 

[redrider]

Math and science, my favorites. It takes a specific amount of horsepower to perform a specific amount of work. Alcohol has roughly 1/2 the amount of energy per equal volume of gasoline. Travel at any speed and you will use more fuel with gasohol than pure gasoline. It surely keeps the farmers in the corn belt happy.

 

[ShadowsPapa]

Besides the engine breaking in, I can think of 2 additional factors.

Fuel and tires. The winter blend of 87 octane likely has 10% alcohol. The summer blend may have none, depending on where you get it in the USA. I can easily see a 10 MPG difference between the two fuels between summer and winter in my Prius. New tires also cut down on mileage since they are more spongy and flexible. As the tires wear, you mileage will improve.

That's not how it works. Ethanol blends must be labeled, and they can't sell you ethanol blend from the pump in winter and then not in the summer. They don't add ethanol depending on season. It's either ethanol or it's not.
10 mpg drop? Nope, I drove multiple Prius and other vehicles for the State of Iowa and we could travel almost as far on 10% blend as we could on pure gasoline. My Silverado saw such a small difference I had to keep a spreadsheet that told me when the price differences were enough to make it worth switching back and forth. I also gained 15 hp and some torque when I used E85.

Waay too much fake info out there from the haters.

Math and science, my favorites. It takes a specific amount of horsepower to perform a specific amount of work. Alcohol has roughly 1/2 the amount of energy per equal volume of gasoline.

Half? Hardly. Check the science sites, not the "I hate ethanol, it sucks" sites.
The energy content ethanol is 76,100 BTU/US gal compared to 114,100 BTU/US gal for straight gasoline. That's closer to 67%. Also -you have to consider that only 10% is ethanol, that means you are lowering the energy content even less than that. You are taking away about 33% of the energy content from only 10% of the gasoline! In the process, though, you are increasing other properties, so it's not a lose-lose.

 

[PyrPatriot]

I also noticed on the last fill-up with gauges showing 20 miles to empty that the tank only took 18.6 gallons to fill up. Was averaging around 15 miles per gallon on the gauges.

I hope this will improve after break in period. Thoughts???

See: https://www.jeepgladiatorforum.com/forum/threads/fuel-tank-capacity-low-fuel-light.24554/

No, fuel economy does not improve. I started out with 20-22mpgs on OEM setup. Adding 35s, rails, bumper, winch, and gear I'm at 15-17mpg city/hwy mix

Not exactly apples to apples, but out stock Sport S with the 3.73 gears will give us about 26 mpg on a long freeway drive, such as San Jose to San Diego and back.

I had 24-25mpg when I left the dealership and for the first 1k miles or so. It went down after that

Half? Hardly. Check the science sites, not the "I hate ethanol, it sucks" sites.
The energy content ethanol is 76,100 BTU/US gal compared to 114,100 BTU/US gal for straight gasoline. That's closer to 67%. Also -you have to consider that only 10% is ethanol, that means you are lowering the energy content even less than that. You are taking away about 33% of the energy content from only 10% of the gasoline! In the process, though, you are increasing other properties, so it's not a lose-lose.

I get 3mpg better using ethanol-free gas

 

[ShadowsPapa]

See: https://www.jeepgladiatorforum.com/forum/threads/fuel-tank-capacity-low-fuel-light.24554/

No, fuel economy does not improve. I started out with 20-22mpgs on OEM setup. Adding 35s, rails, bumper, winch, and gear I'm at 15-17mpg city/hwy mix

It's improved for many of us but then you are not comparing apples to apples.
Of course when you lift these and expose the undercarriage - AND present a taller profile for the air, present a larger tire front for the wind to hit and add more mass to the vehicle, it's going to go down.
So you could indeed say for some Jeep people, the mpg only goes down - lol - because every change you make will reduce the efficiency on the road - but increase it off-road.
OTOH -
If you had a stock JT and checked MPG at say 500 miles and then checked it again at 9,000 miles, ASSUMING same time of year and the vehicle was still stock, it would absolutely improve. Many of us have proven that, and it's been that way since decades ago - and even more-so now with the learning capabilities of the PCM.
Mine went up from 18ish to 22+ at about 7-8,000 miles (same weather conditions) and same equipment.
Only when I started adding stuff to the truck and the dealer flashed the PCM did it drop - and funny thing, it's climbing up a bit again since the PCM has had time to use the new mapping.
Spring will tell when the weather settles, but when our temps were in the upper 40s to lower 50s, I noted it wanted to creep back up in mpg.

I get 3mpg better using ethanol-free gas

That is more inline with my experience with the state cars (and my 2011 Silverado.)
But I found towing to be more pleasant with E85 in my truck because of the added HP and torque it gave me. Hills were easier, less shifting.
To determine which fuel to buy, since ethanol blends are so much cheaper in Iowa, I had to do some math, calculate mpg for various fuel types, the cost differences, etc.

 

[PyrPatriot]

But I found towing to be more pleasant with E85 in my truck because of the added HP and torque it gave me. Hills were easier, less shifting.

With which truck? The JT's user manual states the 3.6L do not handle E85.

 

[ShadowsPapa]

With which truck? The JT's user manual states the 3.6L do not handle E85.

The silverado. HOWEVER - if you've read about the outfit reprogramming the PCM for use with E85 they are getting big HP numbers for this little engine. It's not that the engine doesn't, it's that they never setup the PCM for it.
Even my neighbors little Ford SUV gains 15 hp with E85 and it's a few years old.
I'd be shocked if any part of the fuel system itself couldn't handle it. The PCM doesn't deal with it.
I don't know what's wrong with Jeep in this area. I suppose it's MONEY - it costs for the programming/support.

 

[Gladiator Joe]

I don’t usually post in a thread that has so many variables, but have driven a similar route a couple of times; SC to TX in stock JTR with 33 inch AT’s. I average 20-21 mpg holding at around 73 mph. Checked manually, and for me the truck’s computer was accurate as long as I reset it for the trip.

I have made drive from SC to Miami many times and always get the same at about 21 mpg, holding 73 mph.

I currently have 13k miles on truck. The first time I took a long trip was with a few thousand miles so can’t say if it was lower before that.

Average mixed mpg is 18, but will drop to 16.5 if it’s almost 100% city.

One factor that might make Mojave worse, is I think it has a 1 inch level lift from factory, which certainly would impact aerodynamics.

 

[lrtexasman]

The purpose of my post was really to let some of the folks who are averaging around the fuelly numbers know their vehicle is performing normally. There are vehicle outliers above and below regarding fuel economy. But truthfully, if they are getting around the fuelly averages it is completely normal. Getting above or below is statistically abnormal. Fuelly uses miles driven/fuel added. It is not based off the mileage reader. It can be off if the car is not configured properly (tire size/gearing/cpu). You can look up your past vehicles to compare what you averaged with your driving style compared to others to see if it’s accurate in your case. I have always beaten the averages by around 2 mpg. However, I don’t oversize tires more than +1 or use lifts. I do average 75 mph highway and do very little city commuting.

I think the biggest factor affecting fuel economy for OEM set up vehicles is highway speed. It really starts dropping at 70. So folks who drive 70-80 (very common in Texas) will see lower averages. Also folks who do a lot of city and elevation drives will see a couple mpgs lower.

 

[Oil_Burner]

That's not how it works. Ethanol blends must be labeled, and they can't sell you ethanol blend from the pump in winter and then not in the summer. They don't add ethanol depending on season. It's either ethanol or it's not.
10 mpg drop? Nope, I drove multiple Prius and other vehicles for the State of Iowa and we could travel almost as far on 10% blend as we could on pure gasoline. My Silverado saw such a small difference I had to keep a spreadsheet that told me when the price differences were enough to make it worth switching back and forth. I also gained 15 hp and some torque when I used E85.

Waay too much fake info out there from the haters.




Half? Hardly. Check the science sites, not the "I hate ethanol, it sucks" sites.
The energy content ethanol is 76,100 BTU/US gal compared to 114,100 BTU/US gal for straight gasoline. That's closer to 67%. Also -you have to consider that only 10% is ethanol, that means you are lowering the energy content even less than that. You are taking away about 33% of the energy content from only 10% of the gasoline! In the process, though, you are increasing other properties, so it's not a lose-lose.

I know what the science will tell us about energy content. I can only speak from experience with 200K miles on one Gen 3 Prius, 90K on another Gen 3. Same commute, mostly highway, averages 44 MPG winter, 54 MPG summer.

In Northeast Ohio, the EPA changes the blending of how much alcohol is allowed to be mixed. I see over a one month period in the fall the decrease in economy, and I see an increase in the spring over a one month period. When gas was $4.00 a gallon, there were stories about how there are over 50 blends of gasoline that the EPA relegates on the USA across the country to help with emissions. There was a desire by some people at that time of high prices to cut down on the number of blends to help those with higher prices.

The pump states that there may be up to 10%, it doesn't say there is 10% ethanol. In the winter they typically put 10% in and in the summer, it's reduced.

It's not just the Prius that I noticed the decrease, before the Prius, I drove a Chevy Impala for work, 100 mile commute round trip each day. 22 MPG on E85, 29 MPG on unleaded with 10% ethanol. 75% of my year driving the Impala was on E85, and it was rather consistent at 22 MPG. I filled at a work E85 pump. If I filled off-site because I was not close to my work fueling site, that vehicle would immediately get a noticeable increase in mileage, and as the amount of ethanol in the tank would decrease, the mileage would increase to about 29 MPG when I only filled with standard unleaded fuel.

I'm hardly an ethanol hater. If my Prius would run E85, I would use it 100% of the time, even with a decrease in mileage. I'm just reporting that in my experience, I have observed a reduction in fuel economy with the amount of ethanol in the tank.

I also saw a 4 MPG decrease when I replaced the tires, same brand/model tire.

 

[ShadowsPapa]

It's the butane that's changed more than anything.
97 percent of all gasoline sold contains ethanol—and, according to the American Petroleum Institute, ethanol blended up to 10 percent results in gasoline with a 10.0-psi RVP—the EPA counts such blends, called E10, as meeting the 9.0-psi standard.
Refiners reduce the concentration of butane—a cheaper additive which has a really high RVP of 52 psi—down to about 2 percent.
Because ethanol RVP is only a little more than the rules state the max to be, that's not what's normally cut back. Cutting ethanol content would have little impact on the RVP.
It's the butane.

 

[go0001]

I made a trip to Santa Clara last Monday (1250 miles round trip). The computer showed 21mpg. I usually run 3 to 5 miles over the posted limit, depending on traffic. I have a stock Overland with the street tires, and just over 15k miles on it.

21 mpg max on highway is what I’m getting recently. 2020 JT Overland factory street tires 3.73, hard top, tonneau cover, at approx 5K miles 4 months in. I drive from the Jersey Shore to Boston and back maybe once a month 550 miles round trip. 65-75+ mph in general on highways, passing frequently, 10-15mph over speed limit. Lots of slowing down and speeding up due to the traffic in NY state and CT. Prob about 19+mpg when I’m doing that speed and only going up to 21 mpg when I’m slowing down to 65 mph as I get closer to my destination. I was probably +1 mpg when the weather was less cold.

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