While the Honda Insight and Toyota Prius introduced us to hybrid technology, they also introduced us to styling that was, well, unusual. But today, hybrids can easily be mistaken for internal combustion engine vehicles thanks to hybrid versions of the Honda Civic and Accord, Toyota Highlander, Ford Escape and Lexus RX that look nearly identical to their gasoline counterparts.Hybrid vehicle sales increased from just 9,350 vehicles in 2000 to over 346,000 for the 2007 calendar year. About half of those sold in 2007 were Toyota Prius models, whose production run is expected to reach 450,000 units annually in 2009. The more traditional styling, improved performance and soaring fuel prices have led to hybrids' popularity skyrocketing. Here's an in-depth look at what is making these vehicles sell and a little background on the hottest trend in fuel-efficient transportation.

Hybrids of Today and Tomorrow

Since hybrids have been on the market, their popularity has led to an increase in body styles. Today, consumers have a choice of several sedans, SUVs, a luxury crossover vehicle and even light-duty pickups. (For information about every hybrid currently on the market, click here.)

Most automakers consider hybrids to be the first step on the long road to a transportation infrastructure that is less dependent on foreign oil. There is a general consensus that this road will eventually lead to hydrogen as a fuel source, which is clean burning and plentiful. Since there's a lot of ground to cover before hydrogen fuel is the norm, most automakers continue to focus on hybrid technology, while simultaneously planning for a hydrogen infrastructure in the long-term.

While many of the major car companies already have hybrids on the market and plan to add even more models, Hyundai, Kia, Mercedes-Benz and Mitsubishi have hybrid vehicles in development. In addition, Porsche, Subaru, Volkswagen and Volvo are all considering putting hybrid vehicles into production. (To learn more about future hybrid vehicles, click here.)

BMW has chosen not to get in the hybrid game so far, although the company is studying hybrid technology. Its primary focus, however, is on hydrogen and it is currently testing a small fleet of 7 Series models equipped with internal combustion engines that run on hydrogen. "We believe that, in the end, hydrogen is the solution," Tom Purves, chairman and CEO of BMW North America, said. "We will bring a hydrogen-fueled internal combustion engine to market sometime in the current generation of the vehicle," he said. "Clearly, there are a lot of external factors for this to happen, such as fueling stations."