I don't know how you folks obtain such high average mpg readings. I'm averaging 19.2 mpg. Probably one third of my driving is highway. I took a long trip recently and got 26 mpg (only on that trip there and back). BUt over the last year, 19.2 avg. We have 10% ethanol gas around here, but I always use Top-Tier premium (either Mobil or Costco).