First, let's talk about mileage. The sticker said 52 mpg city, 45 mpg highway. Presumably they listed the city mileage higher because of the braking energy reclamation that occurs with this car. The reality has been that I only get about 44 mpg in the city, but I get better gas mileage on the highway. My record is 57 mpg, though I probably average about 47, even in the mountains. The latest models get even better mileage.
My daily commute consists of about 13 miles (6.5 each way) with about a dozen potential stoplights between here and work, with several hills along the way. My daily commute in Minneapolis was longer, though flatter, yet I managed roughly the same mileage.
The one thing that really kills the mileage on this car is the heater. My all time low was about 30 mpg during a long, cold Minnesota winter, though on average I generally get about a 4-5 mpg drop in the winter. The AC only drops it a little - probably 1-2 mpg. I'm going to go out on a limb and suggest that they cause mileage drops on *all* cars. Also, driving style can make a big difference - up to about 5 mpg based on my personal experiences testing out slow acceleration vs fast, quick braking versus gradual, etc.
Next, let's talk about power. My car has a total HP of about 95. It sounds low, but it's a non-factor. Why? Because the electric motor generates a lot of torque, which means that I can out-accelerate most 4 cylinder, and some 6 cylinder, vehicles on flat roads *and* steep hills. Only the turbo diesels can outperform me cylinder for cylinder I'd dare say. Oh, and the 2004 model has a combined HP of about 135.
Lastly, let's talk about space. My cab space is as big, if not bigger than, most small and mid size cars. Don't believe me? The first thing to realize is that the engine compartment is *small*. Most of this car is taken up by the cab. The second thing to realize is that it has a slightly bubbled top, which gives you more head room. I've had 4 people in the car, no problem, and the all say they're surprisingly comfortable.
Lastly, let's talk about emissions. My car, mile per mile, generates fewer emissions that other cars. Why? Because when the Prius is idle the engine *shuts off*. So, when I come to a stoplight, or I'm backing out of the parking lot, the Prius generates ZERO emissions.
I haven't read the Prius message boards in a while, but I suspect the bulk of the complaints come from the Honda Insight crowd. It's a dumb little two-seater with no power. I suspect the lack of HP causes the engine to work overtime, which is why the gas mileage generally sucks under anything less than ideal conditions.
One final note. Although hybrids are a good way for people like me to feel good about themselves, environmentally speaking, automobiles only account for about 10% of worldwide emissions. The vast majority of emissions come from power plants. The worst air polluters, from what I understand, are the old coal plants that haven't been upgraded in 40 years. But, that's another story.