Our Prius averages 44 mpg, not the 51-60 EPA mpg in the ads. It has been in the shop three times now on recalls. The GPS-controls and display software needs some upgrades to be competitive with other makes. BUT, despite these short comings, my next new car will likely be a Prius. It is a work horse, I can pile more stuff in it than in my Avalon, which is a much bigger car on the outside. Interior head and leg room is also better than my Avalon. Prius style is true 21st century; not some makeover of a 20th century design. It has great voice interaction capability and blue tooth connectivity. And despite being hard to navigate around, the GPS does an excellent tracking job.
Interior storage volume and ease of loading/unloading. Short turning radius. Gear shift lever...action. 21st century style. Interior headroom and comfort. Filling up at the gas tank. Qualifying for diamond lanes in Calif.
GPS software, more intuitive human-interface. Automatic-headlight on-off switch. Road noise mitigation. More sun shielding on GPS panel. A bit more HP, maybe 130-150, but without significantly lowering mpg. Lower height to width ratio to reduce weathering in winds.