91 octane or 87, 2025 BS BL

[Dude]

Let’s use some of the prior numbers with the assumption of 23.5 mpg

Calculate the cost of using Premium 91 octane at $4.15/gallon in a vehicle getting 23.5 miles per gallon and 10,000 miles per year driving:
$1,765.95 per year

Calculate the cost of using 87 octane at $3.61/gallon in a vehicle getting 23.5 miles per gallon and 10,000 miles per year driving:
$1,536.16 per year

Not much of an increase. About 63c per day.

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[jkernitzki]

Let’s use some of the prior numbers with the assumption of 23.5 mpg

Calculate the cost of using Premium 91 octane at $4.15/gallon in a vehicle getting 23.5 miles per gallon and 10,000 miles per year driving:
$1,765.95 per year

Calculate the cost of using 87 octane at $3.61/gallon in a vehicle getting 23.5 miles per gallon and 10,000 miles per year driving:
$1,536.16 per year

Not much of an increase. About 63c per day.

That's assuming no change in mpg across different octanes. With no mileage increase, it's all moot, just go with the cheapest gas (from a reputable source).

 

[Dude]

That's assuming no change in mpg across different octanes. With no mileage increase, it's all moot, just go with the cheapest gas (from a reputable source).

That’s right but also using 91 isn’t a deal breaker at 10,000 miles per year assuming mpg remains the same

My 2022 Badlandls (using entirely 91 octane mostly Costco) has a hand-calculated average of 24.4 mpg from new to March 2024

From March 2024 to today, average is 21.1 mpg with the most recent hand-calculated: 18.3, 18.0, 18.4, 17.9, 19.9 mpg with almost entirely stop n go city driving (mostly hot climate) in the 3/2024 to today timeframe. The mpg drop occurred prior to installing new tires and the AGM Battery.

I haven’t had a chance yet to try the suggestion of disconnecting the battery for an hour or so.

 

[jkernitzki]

From March 2024 to today, average is 21.1 mpg with the most recent hand-calculated: 18.3, 18.0, 18.4, 17.9, 19.9 mpg with almost entirely stop n go city driving (mostly hot climate) in the 3/2024 to today timeframe.

I don’t feel as bad about my mileage now.

Though truth be told, I’ve only got 2200 or so miles on it, so there’s still some “settling in” to be done. I do know it’ll get better once the weather cools.

 

[Wandering Pinto]

From a cost/benefit take, I ran some numbers with interesting results.

YMMV. Literally.

Assumptions:

• Complete fill-ups of 16 gallons
• My local prices today in Metro Phoenix
• Estimated average mpg
• 10,000 miles per year driven
• 2.0L MPC

My main takeaway is 91 would, while costing about 15% more per fill-up, save ~$123 over a year using nearly 30 gallons less than 87 over the same period.

I've attached the spreadsheet so you can do your own comparison.

Octane	Fuel	$/Gal	Cost/Tank	MPG	Range	Cost/mi	10K Mi	Cost Delta	Gallons Delta
87	16	$3.61	$57.76	21.0	336	$0.172	$1,719.05​	$0.00​	0.00
89	16	$3.96	$63.36	23.5	376	$0.169	$1,685.11​	-$33.94​	8.57
91	16	$4.15	$66.40	26.0	416	$0.160	$1,596.15​	-$122.89​	29.61

I can't remember the last time I have seen price spread that low between 87 and 91. It's constantly at a $1 per gallon more in all my travels. That makes it 25% more, not worth it in most cases .I will use 91 while towing if it's hot or hilly.

 

[Mwittke5857]

#1, it has a turbo and unless you're running E85 and it's tuned appropriately, that's IMHO is the way to go for the best overall performance. #2, the cost difference is slight, why would you not? #3 This is a DPI engine and valve jobs are expensive, why not run the better/cleaner burning fuel.

 

[Bill G]

I can't remember the last time I have seen price spread that low between 87 and 91. It's constantly at a $1 per gallon more in all my travels. That makes it 25% more, not worth it in most cases .I will use 91 while towing if it's hot or hilly.

The Costco in my area consistently runs @ $.40 per gal more for 91 over 87 octane.

 

[Wandering Pinto]

The Costco in my area consistently runs @ $.40 per gal more for 91 over 87 octane.

Yes , then it might be worth it. Most of this year in my area 87 has been $2.79, 91 $3.79.

 

[Escape2Bronco]

Yes , then it might be worth it. Most of this year in my area 87 has been $2.79, 91 $3.79.

At most stations in the Midwest, I see about 1.00 difference as well. I always use 87 except in my mowers where I run non ethanol which is only available in 91 or when I plan not to run a vehicle for the winter. 87 is 2.75 at Costco and non-ethanol 91 is 4.19 at Kwik-Trip.

 

[kshaw]

I use 87 octane for all my cars except for the Porsche. Even cars that recommend premium fuel but does not require it, will have knock sensors and adjust timing for your octane level. You may not get the performance that the premium fuel would offer. The Porsche gets 93 octane when I can find it.

 

[Arcee]

Recently bought a Big Bend with the 1.5L. I can only assume it was delivered with a full tank of 87. First fill up I put in 89 and noticed the engine ran smoother. Next fill-up I put in 91 octane and there is a noticeable improvement in responsiveness. Averaged 30mpg with all 3 octanes. The difference with 91 is well worth the minimal added cost just for the increased responsiveness [and arguably better for the engine over the long run.] Just my seat of the pants observations.

 

[Warped9]

Recently bought a Big Bend with the 1.5L. I can only assume it was delivered with a full tank of 87. First fill up I put in 89 and noticed the engine ran smoother. Next fill-up I put in 91 octane and there is a noticeable improvement in responsiveness. Averaged 30mpg with all 3 octanes. The difference with 91 is well worth the minimal added cost just for the increased responsiveness [and arguably better for the engine over the long run.] Just my seat of the pants observations.

I have a ‘24 Big Bend. I’m going to try the 91 next fill up.

 

[Stircrazy]

Let’s use some of the prior numbers with the assumption of 23.5 mpg

Calculate the cost of using Premium 91 octane at $4.15/gallon in a vehicle getting 23.5 miles per gallon and 10,000 miles per year driving:
$1,765.95 per year

Calculate the cost of using 87 octane at $3.61/gallon in a vehicle getting 23.5 miles per gallon and 10,000 miles per year driving:
$1,536.16 per year

Not much of an increase. About 63c per day.

now take that 10000, and change it to 30000 it starts to add up when you drive less than 1/2 the Calander days in a year.

I tested 4 tanks of regular and then 4 tanks of premium going to work and back which is over an hour each way in the mountains. since I bought this car to be a fuel efficient commuter for work as opposed to using my truck, I drive rather nice in it. I set the cruse control about 5mph over the speed limit and let it drive while I drink my coffee over those 8 tanks I didn't see enough difference to warrant using premium, well no difference at all in milage, the premium only cost me more money. I think for people who are not on the peddle harder and doing higher revs a lot, the benefits of premium fuel will be minimum

 

[Poolmanz Sport Bronco]

I Have a 2025 BS BL Sasq. Now 4th tank of VP fuels 93 octane Non Ethanol and averaging 4-5 mpg increase (25.348 mpg at fill today). I drive off road at low speeds most of the time . Don't need to press the accelerator very much. Paying today at $3.39/gal. Will take the BS to Mooresville's HRGoffroad and leave for a week for a 2 1/2" lift kit install. They want to make sure their kit will fit, adjust as necessary for the Sasquatch package and I get to keep the kit.

Awesome deal you got there!

 

[Warped9]

Just filled up this evening with 91 Octane. it cost me about $8 more to fill the tank. We’ll see what difference it makes.

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