My driving habits changed with the prius. When I am driving the prius, I am like those old grannies. I drive very slow <45mph, in the slowest lane, except the freeway. I try to avoid freeway. I always wonder if someone behind me think "this guy already have a prius, yet driving so slowly" or maybe cursing at me. In silicon valley bay area, I also found that I alway get better mileage in the PWR mode. From/to work, mileage average between 62.3 and 65.7. Driving on san tomas expressway from north end or south end, morning commute/home commute after rush hour traffic.
But granny-style driving can actually *reduce* one's MPG (pulse and glide is a step above granny). Not in CD's case...60 and above on average.
I get just the opposite, eco = good mileage, normal = bad. Haven't tried power mode. Did a full tank on eco and got 50.4 at fillup driving normally with mpg display off, did about 1/2 tank in normal mode same setup, couldn't resist and peeked, 46.8. Weather virtually the same, no rain, hot, same commute. Switched back to eco, now back to 50.1. Big variance. Interesting.