Re: MPG and Octane

[John Firestone <john.firestone@xxxxxxxxxxxx>]

On Mon, 23 Sep 2002 jkerouac@domain.elided wrote:

> ... I find that 20+ years of BMW driving shows that higher octane
> fuel always gives better gas mileage, in my cars, the way I drive.

Back in the days when the middle 'M' stood more for Motor than
Marketing, German BMW brochures included a few sentences like the
following [my translation from the Fall 93 E36 coupe brochure]:

   Engines with knock control are designed for RON 95 fuel.  If
   RON 98 is used, the standard fuel consumption will decrease
   by roughly 1% and engine power will rise.  With RON 91, fuel
   consumption will increase by roughly 3% and engine power will
   fall.

At that time and I expect now, the increased fuel consumption largely
erased any expected savings of using regular unleaded (RON 91) fuel.

- -John
'96 318is

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