Alright, this sounds crazy but here goes. Since I bought my CM - Panda- I have been giving her 92 octane and she consistently been giving me about 330 miles with 32 mpg. One day a gas attendant accidentally filled her up with 87 octane. Here is the part that scratching my head. I got 34mpg with about 350miles...... I thought it was the way I drive so, on the second fill, I asked for 87 oct just to see this is repeatable. Guess what? Happened agained - 350 miles, 35mpg. Still scratching my head, So I went back to 92 oct and the result went back to lower mileage with lower mpg. This doesn't make sense but it did. Did anyone noticed this or tried?

Note- I drive 130miles daily, 70-80mph, conservative, 95% highway mon to friday.

Steven

 

Where are you and what's your altitude?

 

Northern NJ, 10 miles west of NYC.

Steven

 

The fuel economy you're receiving will be short lived. The Mini's require 91 or higher since they have a 10.6:1 compression ratio meaning you need an octane fuel that will be able to handle the compression without prematurely igniting (that which causes the knocks). Your computer will eventually retard the air/fuel mixture in an attempt to prevent the knocking and your economy will eventually drop off to worse not to mention start damaging the engine because the computer can only retard the controls sooo much. Depending on the "winterizing" of your fuels, your octane may actually be higher to compensate for the weather and better air temperature rate.

 

If it is a non-S MINI says 87 will not harm the engine.

 

I should have known this before. CM4 will require premium!??!?!?!? I know that higher octane doesn't always mean better fuel normally.....but standard grade might hurt my CM4???
ps: that is one HELL of a commute man!!!! i do not envy you

 

RE: TFM

 

Thanks everyone for the warnings and concerns. I too agree that high performance vehicle requires high grade gas but I always thought that high octane gave better mileage. Live and learn.....

@riff42-yep, it is a hell-of-a-drive. I never knew about road rage at my previous company (9miles, back road drive) until this employment which has been 3 years now. Hopefully I'll be back at the old office next spring. Im hating to see my CM is reg near 10,000 miles in 3.5 months.... Argggggg!

Steven

 

Sweet Jezuz. Time for you to get a motorcycle. Can't get rid of road-rage, but the mileage is wonderful

 

I filled up last night and I was talking to someone and not paying attention and inadvertantly filled my CM S with 87. What should I do now?

 

Just drive it, it won't hurt anything. The Engine Control Unit will automatically retard the ignition, so you will notice a little less power and maybe fewer miles per gallon, but that's all.

You can fill it with premium when you get down to half a tank and that'll boost the octane of the fuel in you tank, the ECU will adjust.

Dave

 

I would add a bottle of octane booster to the tank. See post #7.

 

So 89 not 91 is ok by the book on the S. That is good news. Mid-grade for my area is 89 and is MUCH cheaper than 91 or 93 which is considered Premium around my parts.

 

I found an interesting article from Edmunds.com about one of their long term cars, the Chevy Cruze:

http://blogs.insideline.com/roadtest...s-premium.html

In a fairly non-scientific way, they found that Premium gas was cheaper per mile than lower grade gas for that particular 4 cylinder turbo car.

My personal guess is that MINI tuned the non-turbo engine for 87 octane so thats where it will be the most powerful and highest mpg. I am fairly sure that the turbo S is tuned for Premium; giving us the most power and the cheapest cost per mile.

 

FWIW,

More octane info HERE.