Gasoline octane & MPG

[onestout]

Stock tune on ours and it seems to like 89 octane the best, no idea why. I saw a pretty good jump in mpg going from 87 to 89, a lot more than I expected but I didn't perform the study over enough miles to say for sure. I ran a couple tanks non-oxy 91 and it picked up a little over 89 but not much, the biggest jump for me was from 87 to 89 so we are running 89. My truck with the 3.5 really prefers the 91 to see any measurable mpg increase.

Here the 87 and 89 are E10, when I get 91 it is E0.

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[crenca]

I'm so confused by these good gas mileage numbers. Maybe it's because....

....some of them are quite literally unbelievable - defying the known physics of a 2.5 ton un-aerodynamic vehicle with a large frontal area also with a heavy rotational mass. Perhaps a bronco with a small wheel/tire package, under ideal conditions such as spending much of its time in top gear in the 45 to 50 mph range might be able to just poke its head above 20mpg...but consistently? Unbelievable....


It's a testament to the thermodynamic efficiency of the modern ice engine that I'm able to get about 17 and change out of my SASed Bronco, to expect more given physics and current technology is just not realistic.

 

[PrepVet]

Ethanol and winter blend gas are all going to give you less MPG. It also depends on if you are getting the silly named "top tier" gas or not.

 

[Scott R Nelson]

....some of them are quite literally unbelievable - defying the known physics of a 2.5 ton un-aerodynamic vehicle with a large frontal area also with a heavy rotational mass. Perhaps a bronco with a small wheel/tire package, under ideal conditions such as spending much of its time in top gear in the 45 to 50 mph range might be able to just poke its head above 20mpg...but consistently? Unbelievable....

I have managed over 20 mpg for the 18,000 miles that I've driven my Bronco. It's a 2-door, so not quite as heavy as average, but it's also a Sasquatch. I'll go up to the top of a local mountain and it will show somewhere under 18 mpg, but coming back down the number jumps back up over 20. Going even slightly downhill produces good numbers.

Gratuitous photo way up in the hills a few months ago before the snow came:

 

[KC5MO]

The only difference I got from fuel was 3 MPG better with non-ethanol fuel. The difference between various octanes was not really noticeable. This was hand calculated and not the Bronco's computer.

 

[broncohopeful]

I would bet you settle in at 17.6 running in eco mode, w 89, and driving conservatively.

I hope you obtain over 20 though.

 

[SkyKing]

I use 89 octane on my 2.7L 2021 4-door Wildtrak with aftermarket roof rack and have averaged 19.0mpg overall over 20K miles. I have another car for driving like I stole it that only gets 9mpg at 2500lbs.

 

[Badlux]

22 Badlands, SAS, 2.7. My Scientific Tests.
With 87 Highway 20 / City 16
With 91 Highway 21 / City 17
So basically for $.50 a gallon I gain 1mpg. Then I waste that with the extra power flexing all over the road. So 87 is a better choice.

 

[Techun]

....some of them are quite literally unbelievable - defying the known physics of a 2.5 ton un-aerodynamic vehicle with a large frontal area also with a heavy rotational mass. Perhaps a bronco with a small wheel/tire package, under ideal conditions such as spending much of its time in top gear in the 45 to 50 mph range might be able to just poke its head above 20mpg...but consistently? Unbelievable....


It's a testament to the thermodynamic efficiency of the modern ice engine that I'm able to get about 17 and change out of my SASed Bronco, to expect more given physics and current technology is just not realistic.

4dr BD 2.7 I got 22+ over 35k miles.

Now I put BL wheels and tires on it and it seems like it's getting 20.5

My commute was long, 40-60mph, with few stops.

 

[Poppavein]

Another data point, I get 18.3 with mostly non-highway driving, ProCal on Premium. 35” pizza cutters.

My Range Rover only got 12mpg, so I’m thrilled with what I’m getting.

For the ultimate in performance, I’ll take a motorcycle which gets 35mpg.

 

[Mtea]

2023 BB non-sas 2dr 2.3 auto. I normally run 91 Octane premium and usual get around 24 mpg in the winter snow and all and 25 mpg in the summer on the computer. I check it most tanks and it ranges from 1 mph positive to spot on. Don’t usually drive over about 60 as top limit is 55 around my house. I did do a road trip last summer and got 28 mpg over about 1,000 miles. I run a Trailrax half-rack that might drag it down a bit.

 

[Langwilliams]

you’re getting a noticeable performance improvement by feeding it 91, FOR FREE!

It's no effort to get it but it's NOT free. The price difference varies greatly from area to area. California looks to be about 40/50 cents more (I haven't lived there since '95 so I don't know, just what I thought I saw), in that case I'd run it every time. Here premium is a buck to a buck 20 more a gallon. I buy around 45 gallons a month, that's 45 to 55 dollars a month, $600 a year.

I used to mess around an mix 3 gallons E85 an 15 gallons of plus 89 which worked out to about E20 an 92 octane for about the price of a tank of regular. E85 can be over a back a gallon cheaper here.

 

[PetePerkins]

....some of them are quite literally unbelievable - defying the known physics of a 2.5 ton un-aerodynamic vehicle with a large frontal area also with a heavy rotational mass. Perhaps a bronco with a small wheel/tire package, under ideal conditions such as spending much of its time in top gear in the 45 to 50 mph range might be able to just poke its head above 20mpg...but consistently? Unbelievable....


It's a testament to the thermodynamic efficiency of the modern ice engine that I'm able to get about 17 and change out of my SASed Bronco, to expect more given physics and current technology is just not realistic.

I'm with you on this. I'm almost tempted to ask the age of the folks averaging 22-24mpg. I would assume a person 50-60+ would be a bit more relaxed with their right foot and staying 5-10 mph under posted speed limits.

 

[JAD67428]

I'm with you on this. I'm almost tempted to ask the age of the folks averaging 22-24mpg. I would assume a person 50-60+ would be a bit more relaxed with their right foot and staying 5-10 mph under posted speed limits.

We’ll I can tell you that’s not me, 60 year old and I’m usually 10 mph over the speed limit just not in a school zone tho. I probably get like 15-19 mpg, on average. With the 4cyl. and I fill up with 93 octane every fill up.

 

[Sgt Badlands]

So, I've been getting shockingly bad gas mileage. I've put 1700 miles on my BD in a couple of weeks. averaging 15.5 mpg..... but thats including different drive modes.
Anyway, today, I filled her up with 89 octane, instead of 87, and over 50 miles, (most of it highway), I averaged 20 MPG.
In my old FJ cruiser, I had found that higher Octane gas, especially on highway trips, made a big difference in terms of better mileage. However as the vehicle got older, it seemed like the lower octane fuels were causing problems, even though the FJ was supposed to handle multiple octane fuels.
I dont know anything about what's considered the best fuel to use in the 2.3 engine.?

Where do you live. Fuel is recieving winter additives now. This will bring your gas mileage down.

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