Has anyone done ay experiementation with the various gasoline types that are available at the pump? I noticed the owners manual mentions that Premium gas can provide benefit at higher temperatures, which stoked my curiousity. Its still rather cool where I am (30F's), so the higher temp thing isn't going to come into play for another 3-4 months. I previously drove a 2012 Nissan Altima 4 cylinder. About the 2nd year I owned it, E15 came on the scene where I lived. Instinctually, I figured it would be detrimental to gas mileage. I was surprised to discover that on average, I was getting about 0.5 to 1.0 MPG better mileage on E15 that I had been getting on regular gas (I assume E10, whether it was claimed at the pump or not). It wasn't just one as station vs another, it didn't seem to correlate to season ( I had the car almost 9 year and 108k miles, lots of data), I would consistently get more miles per tank (and calculated more MPG) on E15...which always baffled me, but whatever. Anyway, this got me wondering if anyone has done similar record keeping with their FFE. I'm only about 600 miles into this car, and am totally geeking out on the experience. The two times I've topped off, I put about 75% premium, 25% regular in the tank....purely out of ignorance or curiosity or whatever. Just curious if anyone has any data on fuel type to mileage or performance. Cheers!