I just did my first real practically all-highway roadtrip in the HiHy. Average speed was 60-70MPH for two 3-hour long rides. A very little bit of mountain scenery with 7% downhill grades for a few miles, but otherwise relatively normal highway.

Computerized MPG: 30.2. Actual MPG was just about 1.5% below that in the 29.5 neighborhood (actual numbers in the spreadsheet somewhere). Used 87 octane and ran the AC, if that matters.

What I'm curious about is that my MPG on the highway is that similar to what I get when the majority of my driving is suburban. What's up with that?