Portions Of A 20 Hour Road Trip

Running with the cruise control set on the posted speed limit with non-ethanol premium fuel, I got 30.9 mpg from 30 miles inside Idaho to Portland, OR. On the return trip, I got 31.9 mpg from Aberdeen, WA to Pendleton, OR but then Cabbage Hill happened.
Have you ever had a millenial with his hair in a bun and a big ego driving a Yugo try to get enough speed up to pass you on the interstate?