Explain this - higher mpg with Ethanol
 

I had been religious about using premium in my 06 RX8.

However, I was at a rural gas station in Iowa that had only 10 percent ethanol and I was darn near empty. So I filled it up, thinking one time won't hurt anything.

I'd read that one could expect slightly worse gas mileage with an ethanol blend. Imagine my surprise when I got an extra 50 miles out of that tank. Thinking it was a fluke, I again filled up with ethanol, just as a scientific experiment. I'm halfway through that tank and am again on pace to see my range increased approximately 50 miles.

I can't figure this out, as everything I've heard and read says that ethanol leads to LOWER gas mileage.

Maybe the ethanol is so fresh here in Iowa that it's better> :dunno: (That's a joke, I'm not that dumb, but I do wonder what's going on).

ethanol gives me knocks.

I've noticed no change at all in performance in the two tanks of ethanol I've used.

The blend I've been using has a 90 octane rating, which is higher than the non-ethanol regular here.

e10 is the only thing available here. i have no choice. even shell used a 10% blend.

I've got no choice but ethanol. But there's no way in hell anyone can guess based on the (lack of) info you provide.

So, um, my guess is that you were on a longer trip (hence the fill up in some random IA town) and that longer trip results in 50 miles extra. (mine gets 50-70 miles extra out of a tank if I do trip of 250+ miles)

rural? Don't you have less stop and go traffic hence leading to better mileage...

That's what I thought at first as well - longer trip = greater range.

But the second tank I filled and did my normal routine of driving - back and forth to work, back and forth to the gym, no out-of-town trips, and am still seeing the improved mileage.

Maybe you still had Winter gas form the gas station in the previous fill up.

Recently, I took my car out for a long trip, about 120 miles straight of uninterrupted driving for the first time in it's life. I expected good range out of that tank and I got it. But I did notice that subsequent tanks got better range than normal too.

I'm not that big a stickler on mileage as I prefer to enjoy my car, but it seems a good stretch of the legs might be good for the engine.

No idea.

But hell, I get better gas mileage cruising at 80-85 than 65-70.

Couldn't tell ya. You can only buy 10% ethanol blend gas in the Chicago area, and on the rare occasions when I can buy non-ethanol blend gas, I see about a 10-12% increase in fuel mileage over the ethanol.

???