Another factor to the C-Max not getting the 47mpg on freeways (at 65 - 70mph) could be due to aerodynamics? Seems like the Prius form factor lends to a lower drag coefficient? I work in Walnut Creek, CA so my commute is on 680. I can see that at 65mph, I'm mostly getting around 32-40mpg depending on the elevation along the 680 freeway. My first tank of gas netted 46.2 mpg. So far on the second, I'm getting about 45.5 mpg or so. My commute is about 50% hwy and 50% city/backroads. However, when I'm actually on the highway, I don't normally drive 65-70mph for long. As a matter of fact, since I got the C-Max, I've been driving near 62-65 mph to maximize the mileage. This is possible since during commute time, traffic doesn't go faster than 65-70mph for long. Maybe I'll do some testing with the Trip 2 and reset it during the freeway stretch and see what the average mpg is. Although it's tough to stay at 65mph for long during commute time.