BP bought their way into the US market by acquiring Amoco.

I have also noticed that our 06 MCSa prefers Shell Vpower 91 octane here in both San Diego and Northern California areas. Tried Chevron, BP, 76, ARCO and others every now and then when needed but it consistently drives smoother on the Shell stuff.

 

In the three months of owning my 2005 MCS, I've used Chevron the entire time. I'm getting over 400 miles per/tank in Seattle/Tacoma driving. I'm very happy.

However as I posted on another thread, I just added a can of BG44K to a tank and my miles dropped quit bad. I was ready for it, as the tech that sold it to me said that it may do that. He told me a can every 30K would be more than enough if the car uses top-tier gas and is kept up well. I had just passed the 30K mark so I tried it. My goal was to just clean any carbon that had built up from daily use and two other owners. Just a bit of TLC.

My current tank of Chevron is doing very well. On a run from Olympia to Bremerton (those out here will know the drive highway 16) the car performed outstanding and my gauge changed very little for the 120 mile run. I was at or above 70mph most of the time.

I'm not sure how many types of gas mixtures we get up in the Puget Sound for summer driving, so I don't think I have a solid baseline to judge from.

 

<opinion>
I would expect you to get less mileage from higher octane fuel - if... you don't tune the engine to use the fuel (ignition timing, injection parameters). Higher octane fuel burns hotter and quicker and therefore you would need to have the engine adapt for that. People assume that putting race gas (110 octane) in their bikes (tuned for pump gas) when in fact they get less power. I won't pretend I know specifics or science regarding this, but I believe my fundamental idea is correct.

</opinion>

 

But since MINI recommends premium, I would assume it is already tuned for high octane fuel.

 

Higher octane fuel burns slower and is less prone to detonation (exploding) than lower octane fuel. You are correct that an engine has to be capable of taking advantage of the higher octane for it to be worthwhile. The turbo Audis I have owned exhibited a noticable increase in performance when run with high octane fuel because they have multiple timing maps and will use the most agressive map (most advanced timing) that doesn't cause detonation.
I don't know if MINIs have this feature so I can't say for sure if they are capable of performance increases when run on high octane fuel.
See http://en.wikipedia.org/wiki/Octane_rating for more information.

 

so from all these posts and responses frmo everybody, whcih high octane gas is better for the MINI as far as mileage and performance is concerned?

Shell or Chevron?

(i use chevron cuz its a few cents cheaper, but in the long run, more mileage overcomes the cent difference.)

ive read all the posts but i can figure out which gas is better. its like theyre the same exact thing.

 

I average 29-30 mpg with an average speed of around 24mph..........but, thats with a standard trans and a non turbo coop...........

 

oh.....and with regular gas........never premium....

 

standard........i meant auto

 

Interesting you should say that because I am mostly highway (in CA too) and my on board says avg is about 25.8 I have never seen the likes of 30. I have 30k mi and some minor mods. 17" wheels may make a diff? I would love to see 30mpg with the performance I think I have. I would imagine a 15% SC pulley would help increase MPG also wouldn't it? If you can stay of WOT.