One of the car magazines did a test on this (anyone remember which one???). To sum it up they basically said to run the octane that is reccomended - but any higher and you are waisting $. They tested a bunch of cars - the savings you got from a lower grade of gas was cancelled out by the hit in MPG. Pretty simple, run what the manufacturer says. Now the real wildcard is....how do you know that the gas station is actually pumping what it says on the pump...that's a whole other problem.

 

Branded fuel stations have pretty strict controls......It is Billy Bob's gas station down the road the one you have to worry about........the brands are fiercely protective of their product and reputation.......(and law suits as well).
I agree, more than reccomended is a waste of money, unless you have messed with the car's compression ratio, induction or timing, in which case you will get your moneys worth and MORE importantly, not melt a piston. PINGING IS REALLY BAD people. It will destroy your engine and guess what......it ain't covered by warranty cuz it will be obvious ya did not use the proper grade.........DO NOT LET YOUR BABY PING!

 

I'm in Texas where the octace ratings are 93 and 89. I almost always use 93. I have, on ocassion, used 89 when the price difference was exceptional.

At those times, I could tell NO difference in either performance or milage. Anyone else have this expereince?

 

I don't know... Everything everyone is saying here is going directly against what I read about 2 yrs ago in Scientific American magazine. Some researchers did a big study on this topic across many brands of cars. They determined that higher octane gasoline actually lets off more pollution, and doesn't provide any real increase in MPG. I have been putting 87 in my Mini Cooper since the first day I got it, and have had no problems. I get about 20-25 MPG for the most part, unless I really nail it, which is when you can just watch that fuel gauge drop! :smile:

I'm going to try 91 out at the next fill up and inform you all as to any difference. I mean I might be able to see a difference more clearly since I have ALWAYS used 87. Hope I can help.

Sean

 

I'd like to read that article. Which issue of Scientific American had the octane versus performance article?

 

>>They determined that higher octane gasoline ...doesn't provide any real increase in MPG.
>> I have been putting 87 in my Mini Cooper ... I get about 20-25 MPG for the most part,

Maybe you'd get THESE fuel economy numbers if you used 93.

Here are the numbers for my 02/2002 build MINI Cooper 5-speed with 93 Octane:

 

Just now I went through all of the 2002 issues of Scientific American and could find no articles concerning octane ratings versus performance, but I did find an interesting article which IMO applies to this thread.

Smart People Believe Weird Things is on page 35 of the September 2002 issue of Scientific American. It is a short article and can easily be read and understood in less than ten minutes. After reading the article I now know why so many people believe that it is okay to disregard MINI’s statememt:
“Required fuel:
Premium Unleaded Gasoline
Min. 91 AKI”
Note that MINI does not say suggested nor does it say recommended. They do say requred!

 

>>
>>Smart People Believe Weird Things

There are a LOT of examples of this all over this site..........

 

>>Maybe you'd get THESE fuel economy numbers if you used 93.

BAM! (you should have TOTALLY added that after your line above! :smile:

The experiment started today. I just filled up with 93 at $2/gal. I'll definitely report back, since my car is a special case. I've ONLY used 87 in it from break in to today, which is somewhere near 18K miles. I'll report back to you guys in near the end of the week, when the tank runs out and I can get a good average MPG out of it.

PS: I will try to find that Scientific American article. It was a while ago and I don't have my back issues. I've been reading that mag for way too many years, so it could be from the late 90's too. I'll try to find it though.

 

I did a search of Scientific American for both octane and AKI and couldn’t find anything that had to do with fuel consumption or performance. Maybe the article was in another magaizine?

 

http://auto.consumerguide.com/auto/e.../act/feature21

Try the above link. I think it very clearly answers everyone's questions, and proves my initial post wrong. I had gone on this SciAm article for years now.... poor Murphy. (my Cooper) I better reward him with a full detailing this weekend!

Again, I'll look up the SciAm article. It was definitely in there, because it's the only science mag I read. It might have been years ago though.

 

seanandcandace - - thanks for the excellent link. Well done!

 

seanandcandace, I would recommend at least a couple of tanks of 93 before making any conclusions (but feel free to report back your results after the first tank)

The engine software may have some "learning" effect, so it may take a couple of tanks (or more) of 93 to get rid of the learning effect from running 87.

 

>>>>So higher octane does equal better mileage?
>>
>>Using the correct octane gives you the best fuel economy.
>>
>>Using too low an octane causes the engine to retard the spark and you get worse economy.
>>
>>Using too high an octane causes the fuel to burn poorly, and causes lower fuel economy.
>>
buck up pay for the fuel .Read the specs before you buy
it's a sports car not an econo box
I know it drives you U.S MINI owners nuts but I get 40 MPG. sure it's bigger than yours[the gallon]but I get that from not hitting high rpm's.I,m still having a fun time
run one curve if it's clear at 110 mph
if we go easy ,good mpg
if we go hard, bad mpg...simple

 

>>Branded fuel stations have pretty strict controls......It is Billy Bob's gas station down the road the one you have to worry about........the brands are fiercely protective of their product and reputation.......(and law suits as well).
>>I agree, more than reccomended is a waste of money, unless you have messed with the car's compression ratio, induction or timing, in which case you will get your moneys worth and MORE importantly, not melt a piston. PINGING IS REALLY BAD people. It will destroy your engine and guess what......it ain't covered by warranty cuz it will be obvious ya did not use the proper grade.........DO NOT LET YOUR BABY PING! :smile: curves :smile: