Here's some thoughts after six months.
- Without trying too hard, it seems easy enough to average 50 mpg in the summer (I've definitely noticed the mileage going down as the cold weather approaches - partly this is because winter gas blends are less energy dense, partly I suspect because the system doesn't have time to reach its optimum operating temperature on a short trip). That would represent a saving of maybe 150 gallons of gasoline per year. Each gallon of gas is responsible for about 9kg of carbon dioxide emissions (source: EPA) so that means our switch reduces our family's annual emissions by about a ton and a half. Not bad. But, as I posted before, it pales in comparison with air travel: one round-trip to Europe will release roughly as much carbon dioxide as our Prius-driving will save us in a year.
- I do think the car has an "educational" effect (at least on me). Having instant feedback about fuel consumption and whether I am running on electric or gasoline power encourages me to drive more economically. Moreover, acceleration is kinda leisurely and I find myself adopting a more relaxed driving style that goes with that. All to the good I suppose. On the other hand, a negative educational effect is possible too. Perhaps, driving a car that carries the social "message" of the Prius can insulate the operator inside a bubble of passive-aggressive moral smugness. A study reported in the New York Times suggests that drivers of "high status" vehicles are less likely to behave courteously towards others, and Prius drivers are up there with BMW drivers in terms of discourtesy.
- Finally, the obvious point: in the end it is another consumption item (despite my perhaps disingenuous use of the word "invest" earlier). I referred just a moment ago to the "social message" of the Prius, thus providing an excellent example of the prevailing ethos of consumerism: the car we drive is not just a metal box on wheels, the stuff we buy is not just stuff, it is a way of conveying who we are. Raising consciousness about the environment is all very well: but will it simply be co-opted to generate another niche market sector, which can increase overall sales still further? This is the "business case for environmentalism". Who shall deliver us?