Although this may have been asked already, I was just curious as to what fuel most NAH owners are using. I've been using 87 octane from Chevron, Mobil, and Shell... but I was thinking of switching to 91...

87 straight gas. No E10 10% ethanol.

Hand calculated numbers, not trip computer data.

87, any car that has 87 as the required/recommended fuel will see very little benefit from a higher octane rated gasoline due to compression ratios not being high enough to harness the extra energy

wow, you can find non E10 gas? you can't find that here in MA. no wonder your MPG is so much higher than mine. ethanol only outputs maybe 1/4(???) the amount of heat as isooctane

I just switched to straight gas on my last tank. Not sure it improved MPG, but it stayed the same, even with the temps getting colder. So, I suspect there was a slight benefit.

Hand calculated numbers, not trip computer data.

Do your gas stations actually state that they're using E10? I've only noticed that something on a Shell station here that stated something along the lines that E10 "may" be used at this station. I've definitely noticed some erratic mpg #'s the few times that i've filled up there.

As a side note...what if I put some iso-octane in the tank as an additive... it would presumably burn more efficient right?

It says it right on the pump in my town.

Hand calculated numbers, not trip computer data.

they have a sticker on the pumps that tell content, everyone in MA says Ethanol 10%

no it will not presumably burn more efficient. you need a higher compression ratio or turbo in order to fully take advantage of a higher octane fuel. just save your money and keep the regular in w/o any additives.

Unleaded Regular will give you the most bang for your buck, the midgrade and Premium contain a combustion retader to reduce compression stroke detonation (anti knock )
If your car is not knocking then you would be wasting your money by using premium...

not true actually. the "combustion retarder" is really is just another way of saying higher octane

and cars these days have anti-knock sensors that retard or advance the spark timing depending on conditions (fuel, weather, heat, etc). it's not wasting your money to put in premium into a car that's not knocking....like I said, the sensors will prevent knocking, but if your engine is designed to handle premium fuel, then you may see better fuel economy with premium. with that said, the NAH is not designed for premium fuel so putting premium into the NAH is a waste of money