Gas Grade and Mileage

SouthArk370Z

It depends on how they adjust the octane at the refinery, but, for all intents and purposes, octane has no effect on MPG. The most important parameter is energy density (eg, BTU/lb or kj/kg) - which means that ethanol "enhanced" fuels will give poorer MPG.

The engine is already pretty efficient so your driving habits will have more of an effect on MPG than mods.
Cooler air is nearly always a good thing, so some type of CAI may be beneficial.
Using "thinner" lubricants in the engine, transmission, and differential can give some gains, but at the risk of poor lubrication at higher temperatures (eg, tracking - but if you're tracking, you're probably not too worried about MPG). Don't do this without doing a lot of research first.
None if these will give big gains - the main thing is to keep an egg on the accelerator pedal.

Edit: And don't run less than 91 octane except in an emergency. Put in just enough low octane fuel to get you to some 91 and drive like your Grandma until you get the good stuff.

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