On Sat, 16 Apr 2005 05:00:54 GMT, Milleron
<millerdot90@SPAMlessosu.edu> wrote:

>>The reason is compression ratio. If you have a high enough compression
>>ratio, then 91 octane is able to give you more power. If you want
>>economy, the knock sensor will dial back your ignition advance, you
>>will have less power, but better fuel econmy.
>
>In the FAQ, I thought it said "less power and LESS fuel economy."

Less economy in actual miles per gallon. But if the gallon costs
appreciably less...

>Which is correct? If the lower octane will definitely give better
>fuel economy, then I can live with less power, but that's not how I
>thought it worked. Please explain further.

Fill your tank with 87. See how many miles it gets you for how many $
Fill your tank with 91. See how many miles it gets you for how many $

Ignore miles per gallon. How many miles per dollar did you get?