Brian. Although it is probably possible to get that kind of mileage it would next to impossible to do real world situations without infuriating everybody else on the road. I have averaged 56.2 mpg over the life of my 2006 Prius in mostly suburban driving of 30-45 mph in a warm, flat area of the US. I do try to strive for the best fuel economy I can and will sometimes play with the hypermiling tricks if nobody is around but when in traffic (most of the time) I just go the speed limit. Summer is better than winter. My current mileage on this tank is displayed at 67.3 mpg (usually ~2% optimistic) at about 250 miles on the tank.

As to the the 37 mpg at 60mph and 30 mpg at 80 mph. It is pure rubbish. I'm not sure I could ever get the Prius to 30 mpg no matter how I drove it. I've had mine on a couple of trips from Phoenix to the San Juan mountains in southwestern Colorado. Vacationing, I take the more scenic and relaxed secondary roads and will keep it at about 60 mph. On both trips of over 1000 miles including going over several 10,000' mountain passes on each trip I've averaged over 50 mpg on both times.