Here in the San Francisco Bay Area of California the premium gas is 92 Octane, using (R+M)/2 AKI, which isn't high enough for my M5.

I've tried several "Octane Booster" additives which help but may not be the best for your car nor do they raise the Octane much, remember they are rated in .1 units so a "6 point" additive only increases the specified amount of fuel ~~ .6 !!!

I have found one "76" gas station which carries:

"76" 100 Octane Unleaded Racing Gasoline is a specialty fuel designed for the performance enthusiast who prefers a high-octane fuel. It is suitable for both racing purposes and high performance vehicles. It will not harm catalytic converters or affect the oxygen sensors on late model, high-performance, specialty engines.

Production of "76" 100 Octane Unleaded Racing Gasoline is carefully limited and strictly controlled to a specific fuel blending recipe comprised of essentially pure components."76" Competition 100 Racing Gasoline meets all State & Federal requirements for CARB Phase II and EPA reformulated Gasoline (RFG). It contains MTBE which is an oxygenate. This product may be sold in all fifty states.

(Above copied without permission from one or more "76" web pages)

The station is located in the South Bay at Almaden Expy & Foxworthy.

I mix the 92 Octane with the 100 to obtain the Octane I want:

1:1 96.0, 2:1 94.6, 3:1 94.0, 4:1 93.6, 5:1 93.3

For example, a nearly empty gas tank (18 US gallons):

9 + 9, 12 + 6, 13.5 + 4.5, 14.4 + 3.6, 15 + 3

As of 2001.03.13 I paid $1.89 for 92 and $4.09 for the 100.

I find that the 3:1 works great for around here, so that works out to $3.54 per gallon.

I have recieved a few E-Mail's and one posting that mixing different Octane rated gas doesn't average ?

Well, I have read over the years various articles both in print and now on the Internet which all either suggest or specify that they do, so the info that follows is based on this assumtion.

I did however do a google.com search on "Octane mixing" and here are some of the links I found:

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