Awhile back I noted an article in the Washington Post that observed that a major reason why many people bought hybrid cars was the same reason that many other people buy a Corvette or Mercedes--because of the image the car projects to the world. "The Prius and Civic have similar new technologies, so it's not just fuel efficiency that's causing drivers to flock to Toyota's hybrid. 'The Prius is a fashion statement,' said Art Spinella, a consultant with CNW Marketing Research who surveys car-buying trends. 'It looks different. Other people know the driver is driving a hybrid vehicle. It clearly makes a bigger statement about the person than does the Civic, which basically looks like a Civic.'"
But that only explains why people buy a Prius hybrid instead of a Civic hybrid. An article in today's Washington Post explores the larger question why do people buy a hybrid car in the first place. I don't doubt that some people do so because they believe that it is better for the environment. But the Post observes that, at least in the DC area, the primary impetus for rapid sales of hybrid cars is that they are allowed to use HOV lanes during rush hour. From the article: "'I'd say 95 percent of the people who buy a Prius say it's to get into HOV,'" said Jay Taye, sales manager at Ourisman Fairfax Toyota. "'They talk about the tax break and the HOV, and once in a while they say they prefer it for the gas mileage as well.'"
In fact, single-occupant hybrids are becoming so commonplace that they are clogging the HOV lanes. "'For every two cars, there's one hybrid,'" said Cora Seballos, who carpools daily from Springfield to the District. "'Since September, usually the regular lanes have less traffic'" than the carpool lanes. Seballos said she has to leave home a half-hour earlier because of the increased congestion."
As for the "environmentally friendly" effect of hybrids, note that in the Post story the hybrid exception is for HOV-3 lanes on I-95. To justify the exception, therefore, a hybrid would have to be three times more environmentally friendly than a standard car to justify the exception. So leaving aside questions that have been raised about whether hybrid cars even are more environmentally-friendly than standard cars, I am not aware of any argument that they are three times more efficient.
An interesting test of the economic hypothesis would be the prevalence of hybrid cars on I-66 (HOV-2) versus I-95 (HOV-3). If the environmentalist hypothesis is correct, then people will have an economic "taste" for hybrid cars, meaning that the decision to buy a hybrid car should be largely independent of the practical benefit that a driver derives from ownership. If the economic theory is correct, then there should be a greater prevalence of hybrid cars on I-95 than I-66 because of the greater tangible benefit in terms of HOV travel. To the best of my knowledge, no one has tested this proposition, but I have my own hunch as to which would likely fare better.
I should add, in my book, The Onion's famous story still remains perhaps the most accurate assessment of public opinion toward these sorts of issues--"Report: 98 Percent of Commuters Favor Public Transportation For Others"
THREE TIMES BENEFITS: To clarify, in response, to a question, I'm using three times benefits as a rule of thumb here. Variables push in different directions, so I am using as a rule of thumb those who used to carpool in HOV-3 becoming single occupant hybrid drivers. But there could be many variables pushing in many directions. Some people could switch from single-passenger traditional cars that they drive in non-HOV lanes to hybrids, in which case it is a net benefit. For instance, one possibility is that some of those who used to take Metro public transit might switch to driving a hybrid if it was perceived as more environmentally-friendly than a traditional car, but more convenient (but still less environmentally friendly) than being an additional rider on the Metro. In that case there is a net detriment. To the extent that the effect is to increase the number of cars and thereby increase congestion (and increase travel times), then this would be weighed on the other side. The Post story (which is, of course, nothing like a serious study, so everything should be taken with a grain of salt) suggests that the overall impact has been to increase the number of cars on the road.
For an argument that the correct ratio should be "about one-and-a-half times" see here. The argument there is that people don't just drive their hybrids to work, so there is some benefit to be accrued from people driving hybrids instead of regular cars during non-commute time. Of course, both of our calculations are pretty arbitrary, but I think the larger point is that in order to justify an HOV exception, I think the benefits would have to be some multiple of the difference between the two types of cars to make up for the loss of HOV drivers, whether that is 1-1/2 times or 3 times. Also, this excludes other psychic and other benefits or detriments that might accrue.