Long drive into Michigan nets varying mileage

I recently returned from a long weekend of driving into and out of Michigan. I skied the 50K Vasa race which is quite a challenge for a weekend warrior such as myself. It took me 3 hours 30 minutes to cover 31 miles of rolling hills-some very steep. This was "only" about one hour slower than the winning time. Any ways, I ran a mostly E10 or E0 into Michigan and average around 28 mpg. Leaving Michigan I ran mostly an E20-25 blend with gas mileage between 27 and 29 mpg. I did drive several miles per hour faster going into Michigan but the difference between the E20 blends and E10 blends in regards of mileage remain non-signficant. I'm going to keep using ethanol blends as often as I can.