The first mass-produced hybrid car for the US and global market still remains king of the green car segment despite some worthy competitors.
I think we can safely say that we all know what the Prius is at this point. The first mass-market gas-electric hybrid to hit the Japanese market in 1997, it was the second to hit US shores in 2000, and hybrids as a whole didn't take off in any market until its introduction. What's interesting about the Prius is not its popularity in the automotive market as a whole, but rather how much more popular it is than every other "green" car on the market.
The first gas-electric hybrid was built not too long after the introduction of the internal combustion engine. This car was the Mixte, built by Dr. Ferdinand Porsche and the Lohner company and unveiled at the Paris World's Fair in 1900. Hybrid busses were being used in England as early as 1901, and the first hybrid race car appeared in 1902. The US military was using hybrid busses in the Twenties, but the real work on modern hybrids began in the Sixties, and picked up momentum during the Energy Crisis in the Seventies. Because so much momentum came from this fuel shortage, the technology again went on the back burner once gas once again became cheap and plentiful.
On the plus side, since the technology was no longer being rushed to market, when it finally did debut in 1997, it was a far more impressive accomplishment. That said, the hybrid was slow to take off, very slow. Toyota sold just 300 of them in '97, and although this was only for the Japanese market, it's still a low number. The big worldwide launch came in 2000, and even with all the early adopters, just 19,500 were sold that year. However, sales have picked up, and as of April of this year, Toyota has sold 2.87 million units, with a total of more than 4 million units for all Toyota and Lexus hybrid models.
Those aren't especially impressive figures when compared to some other Toyota models. For example, Toyota sold 1.36 million units of the Corolla just in 2005. But the Prius is unrivaled in its class. Honda makes the runner up in hybrid sales, the Civic Hybrid, and they've sold only about one tenth the number of those as Toyota has sold of the Prius. Even the combined sales of the Civic Hybrid and the Insight, the cheapest hybrid in the US market, the total still comes to less than half a million. Not only that, but hybrids aren't the only green cars. Volkswagen has made the diesel Golf since 1974, and diesel technology hasn't exactly been standing still.
The current Golf TDI BlueMotion gets fuel economy numbers at least as good as the Prius but is infinitely more fun to drive. So why does the Prius so completely rule its segment? The answer is complicated. Timing has a lot to do with it. Even though the Insight was actually the hybrid for sale in the US, it wasn't anything anyone would really want to buy. The current Insight is somewhat better, but the first Insight was punishment to drive, and only the most determined of early adopters went for it. So the Prius was the first hybrid which was passable as an actual car, not great by any means, but not such an obvious compromise in the name of fuel economy.
So the fact that the Prius was the first hybrid that anyone might conceivably want to buy certainly didn't hurt. But with such a huge gulf between the Prius and its nearest competitor, there has to be another reason. This reason, it seems, is perception. The fact that hybrids tend to be more popular with the green crowd than diesels can be explained simply enough by the belief that the new technology just has to be better than the older technology. Flawed though this thinking might be, there is a logic to it. The other factor in the perception of the Prius is its styling.
The interior is made to look as futuristic as possible, thus better highlighting the newness of the technology and helping the customer to get excited about it. It's gimmicky, maybe, but it's hardly different from the fighter jet styling touches on cars in the Fifties, and can really just be called good marketing. Thus, we can explain why the Prius has sold in better numbers than the Golf TDI and the Insight, but the sales lead over the Civic Hybrid is best explained by way to the exterior styling. The Prius is not an especially good looking car, but it is immediately recognizable.
While the first generation of the Civic Hybrid simply looked like the contemporary Civic, when you have a Prius, people know you have a Prius. Conspicuous conservation is now a noted social phenomenon, and "green" products which call attention to themselves always sell better. The Prius does get good mileage, that can't be argued, it does what it advertises, but it is so successful because it is so much better at advertising it.