I notice a 5 to 7 MPG difference in so-called 92 or higher octane rated fuels here in Florida. Here in Palm Beach where fuel prices are the highest in the state, fuel quality su_ks, when I fuel up let's say in Melborne the fuel is better not to mention cheaper, so much better that 5 to 7 MPG and sometimes more are the norm, in all of my rides, 87 IROC, 3 volvos, and a 2 wheeler.

Is it really the fuel quality, or is it related more to natural causes such as biometric pressure, humidity, elevation an such, or?

 

It's related to a great many things, really.. heh. Gas quality, air temperature, elevation, what kind of terrain you're driving across (flat? hills?), what kind of traffic you're in (more city than highway, or more highway than city?) etc., etc.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

Interesting, I never noticed a fuel milage difference between using higher octane vs. lower octane fuel.

I'd wonder if it was more the "mix" used, not the octane.

I/e I did notice a drop in MPG's when Ca. went to the oxegenated fuel.

 

Yeah, I get about 1-2 mpg less in California, due (I suoppose) to MTBE Oxygenated additives.Also, as of August, no more 92 in CA.91 is now the best we can get.
-Rich-