[glowbalgroup]

I cant prove it but it seems i have better gas mileage with 94 octane VS 91 is this possible?

[verysideways]

On cars i've had in the past this has been the case from time to time.

My old E36 328i Sport definitely got 10% better economy on high octane fuel, whereas my F31 340i didn't seem to make any difference at all, to economy or performance.

Might have to try the good stuff in my M40i now...

[chicagofan00]

I wish we got 93/94 octane around here. A vast majority of the stations around here in AZ only have 87/89/91.

[AndroidRobot]

The only way to truly prove this is in a controlled environment: lab test

[AnOldBiker]

You 'might' get slightly better performance with higher octane, but if you vehicle isn't designed and tuned for it, you running a hotter burning fuel and spending lots more for it.

[Roundel-NY]

Originally Posted by AnOldBiker

You 'might' get slightly better performance with higher octane, but if you vehicle isn't designed and tuned for it, you running a hotter burning fuel and spending lots more for it.

This is not how octane numbers work... the higher the number, the slower the fuel burns.

[AnOldBiker]

Yes, the higher the number, the slower the burn, the hotter the ignition explosion.

[darrylo]

Could this be due to winter fuel formulation, where you have less energy per gallon in the winter?

[nogren]

I believe modern engines adjust constantly, to be as efficient as possible.
When I did quite detailed real life measurements before, it was hardly worth it. It cost 5% more, and was 5% more efficient. On the plus side you actually had a tiny bit more power when needing it.
(In a SAAB Turbo V6)

[AnOldBiker]

Originally Posted by darrylo

Could this be due to winter fuel formulation, where you have less energy per gallon in the winter?

Unless each state changes their requirements, the major difference between winter and summer blends is the vapor pressure.

[MechX3M40i]

First thing first, low octane fuel like Diesel actually have higher energy density than petrol. So the gas mileage of diesel is almost always higher (with the correct engine of course) since they have more energy to give per unit volume of fuel. So this one single factor is opposite to the hypothesis of high octane fuel gets better mileage.

Higher octane is more resistant to knocking, and in theory has a slightly higher efficiency in burning (but not more energy to give, see above). A few more factors to consider:

Does the engine design for it? in our engines with high compression ratio, it's best to pair it with high octane gas (petrol) so the burning is smoother and no timing issues.

Fuel mix additive - do they add alcohol / ethanol to the fuel? These fuel additives typically have much lower energy content vs gasoline itself. so for our experiment to work, we cannot compare premium high octane gas with no such additive vs 87 octane adulterated with additive.

[glowbalgroup]

I can confirm i get better MPG with 94 Octane VS 91 its crazy the difference.
This is what i did.
Local Member and I both have exact same M40I same generation and production period.
Same rims and rubber. KM on both vehicles within 250KM of each other. Both vihicles weighed with driver, I was 65LBS heavier. Hence he addedd 65LBS to his ride.
He has always filled up with 91 for the last 7 tanks i have only used 94
We both filled right to brim side by side at Chevron in Tsawwassen not a drop could be squeezed in the tank in both cars. We both drove out side by around the mall back area loop with ZERO Traffic around us and zero stops. Comfort mode both cars speeds between 60 KM per hour and 100 KM per hour. Side by side same speed using cruise control to accelerate at same pace at same time.
Both of us drove 203.5 KM that included back to the gas station side by side.
When we both filled up again right to top.
His car using the 91 Octane had to put in 19.1 litre of fuel
My car using the 94 Octane i had to put in 17.2 Litre of Fuel
Almost a full two litre difference.
Cost for 91 octane here is 1.43 per litre
Cost for 94 octane is 1.47 per litre

Now after we were done. Both of at a red light side by both in sport mode we both floored it off the light when it went green. I swear we both launched the same time after about 4 or 5 block straight away i was a full 4 or 5 feet ahead and looking like i was pulling further ahead.
Take it for what you want i think i did a pretty controlled environment best i could the difference is very noticeable.
For those who dont know in Canada you get 94 Octane from Chevron
In the US unfortunately you guys dont get 94 Octane. Unless you ask Trump then its huge and you guys have the best gasoline ever LOL sorry had to do that.
93 is the top you guys get and thats only in the following states that i know of.
Georgia
Massachusettes
Maine ONLY at Shell
North Carolina
Pennsylvania
Rhode Island
Texas
Tennessee
Mosty of the above states its Shell who sells 93 primarily

[MechX3M40i]

Originally Posted by glowbalgroup

I can confirm i get better MPG with 94 Octane VS 91 its crazy the difference.
This is what i did.
Local Member and I both have exact same M40I same generation and production period.
Same rims and rubber. KM on both vehicles within 250KM of each other. Both vihicles weighed with driver, I was 65LBS heavier. Hence he addedd 65LBS to his ride.
He has always filled up with 91 for the last 7 tanks i have only used 94
We both filled right to brim side by side at Chevron in Tsawwassen not a drop could be squeezed in the tank in both cars. We both drove out side by around the mall back area loop with ZERO Traffic around us and zero stops. Comfort mode both cars speeds between 60 KM per hour and 100 KM per hour. Side by side same speed using cruise control to accelerate at same pace at same time.
Both of us drove 203.5 KM that included back to the gas station side by side.
When we both filled up again right to top.
His car using the 91 Octane had to put in 19.1 litre of fuel
My car using the 94 Octane i had to put in 17.2 Litre of Fuel
Almost a full two litre difference.
Cost for 91 octane here is 1.43 per litre
Cost for 94 octane is 1.47 per litre

Now after we were done. Both of at a red light side by both in sport mode we both floored it off the light when it went green. I swear we both launched the same time after about 4 or 5 block straight away i was a full 4 or 5 feet ahead and looking like i was pulling further ahead.
Take it for what you want i think i did a pretty controlled environment best i could the difference is very noticeable.
For those who dont know in Canada you get 94 Octane from Chevron
In the US unfortunately you guys dont get 94 Octane. Unless you ask Trump then its huge and you guys have the best gasoline ever LOL sorry had to do that.
93 is the top you guys get and thats only in the following states that i know of.
Georgia
Massachusettes
Maine ONLY at Shell
North Carolina
Pennsylvania
Rhode Island
Texas
Tennessee
Mosty of the above states its Shell who sells 93 primarily

Have to admire your dedication of running the side by side experiment. Give your teammate a shout out here too!

If you guys feel like adding to the study, next time swap the octanes of gasoline and see if the performance results will reverse.

[MattXYZ]

We have 98 RON here in UK - it’s Shell VPower. I’ve used this on all my previous petrol cars. It definitely feels like it produces more power - not sure how much affect on mpg it has. It is also advertised as having additives that help clean the engine.

We also have 99 RON but it’s Tesco supermarket fuel - I generally avoid supermarket fuel. There been reported issues in the past.

I believe the lowest octane petrol we have in UK is 93 RON.

[bsperry92]

In Florida we have 87/89/93. Very few stations have 87/89/91/93, mostly Sunoco. I didn't do an in depth analysis as glowbalgroup, but I did seem to get a bit better range on 93. Not sure if its worth the $0.50 or more per gallon bump in price for 93 though.

[muzzalad]

Originally Posted by MattXYZ

We have 98 RON here in UK - it’s Shell VPower. I’ve used this on all my previous petrol cars. It definitely feels like it produces more power - not sure how much affect on mpg it has. It is also advertised as having additives that help clean the engine.

We also have 99 RON but it’s Tesco supermarket fuel - I generally avoid supermarket fuel. There been reported issues in the past.

I believe the lowest octane petrol we have in UK is 93 RON.

I was always partial to a bit of Tesco 99 for the N55 in my old M135i. Was convinced (possibly placebo) that it made a few more pops.

The Germans get 102 Octane from Aral. Gave my M135i a couple of tanks of that when driving through.

I think the US have a different measurement to Europe. RON in Europe v RON+MON avg in US I believe. Means the lower US numbers are actually in line with Europe. So US 93 is about 98 in Europe.
I'm sure this very knowledgable forum will correct me if I'm off the mark though.

[Max Well]

Originally Posted by glowbalgroup

I can confirm i get better MPG with 94 Octane VS 91 its crazy the difference. This is what i did. ...

Well-scripted real world study, glowbalgroup.

Some other variables to keep in mind, though, as this MPG stuff gets really complex. In an earlier thread I tried to see if wheel weights and tires make a difference, not so much from a pure fuel efficiency standpoint, but rather an aerodynamic and rotating mass standpoint. But it became clear as my 'study' went along that temperature and related DA issues as well as tire pressure are key determinants in end results, and would make it virtually impossible for me to identify relationships with reasonable certainty. For example, if we don't know the exact tire pressures of both of your vehicles it is hard to equate the values you both derived, although you did a great job controlling the other major ones.

As can be seen in the charts in that thread, my MPG in our 2018 G01 X3 M40i, following the exact same routes on multiple trips at same HWY speeds of 79 mph on cruise control without aggressive maneuvering, varied from 23.8 to 29.0 MPG. And that is with the 'same' 93 octane gas (ie., the same stations for the different legs, obviously not the same gas load compositions). https://x3.xbimmers.com/forums/showt...1440682&page=1

Well done, however, and look forward to more data!

[iManu]

Weirdly, I do less km per tank when I use 94 octane from Petro Canada. My best Mpg was with costco gas 91!

[glowbalgroup]

The reason i guess i get better gas milegae on 94 Octane at Chevron is wait for it....................The 94 at Chevron HAS ZERO Ethanol
Read this amazing article
https://axleaddict.com/misc/Pros-and...Ethanol-in-Gas

[Scottatah]

Another canadian here. Petro is my convenient gas station of choice, they offer 87/89/91/94. 94 is only like .05 more than 91 so I've tried it a number of times when I felt rich. This was earlier on when I was monitoring and measuring my gas mileage each fill up. I didn't notice any specific improvements of 94 over 91.

The only consistent thing I've discovered is that my gas mileage went down as the vehicle got more KM and presumably I began to drive more spirited.

One thing I will comment is the trip computer gas mileage and my manually calculated mileage have always been 100% correct. This is positive news to me as I generally hear people suggest they're very inaccurate.

I stopped measuring after 7000 ish KM as I trusted the trip computer and i just got a little lazy. Plus it's slightly more depressing to see gas mileage continually going down. I have no doubt snow and turning off DSC is contributing to lesser gas mileage at the moment (officially hit 11.1 l/100km the other day).