I've had my 2004 Prius for a bit over two years and liked it enough to buy a second one. I just filled up my new 2006 for the first time and noticed that although the mileage on the display screen reset to zero, unlike the 2004, the MPG readout did not reset. I am wondering if this is a new feature or if there is some setting that I don't know about that controls this behavior.
There have been some improvements in the 2006 that I like. The rear camera makes backing up less stressful. Because of rear visibility, I always worry about backing over bicycles, pets, children, etc. Now a quick look at the display screen before backing assures met that the area behind me is clear. The navigation system also seems better. My 2004 thinks that I live out in the middle of a field while the 2006 knows where my driveway is. The voice command system, in addition to responding to more commands, seems to be less picky about pronunciation. It is now possible to set a destination address via voice command while moving. The 2006 does not have a tape player, but the CD player plays MP3 and WMA files, so I guess that's an even tradeoff.
I drive both cars during the week and I can detect absolutely no difference in the way that they handle. The 2004 gets driven on fewer short trips so it is getting about 5 MPG better than the 2006.
Kari