In March, sales of hybrid, plug-in, and clean diesel cars grew significantly in the United States, casting a positive light on the emerging low emission transportation industry.

According to statistics compiled by HybridCars.com and Baum & Associates, a Michigan-based market research firm focusing on automotive issues, hybrids sales totalled 48,205 in March compared to 36,222 in February -- a 39.6% increase.  Even more, hybrid car sales have grown 37.2% to date in 2012 versus the same period in 2011.

Toyota remains the most popular choice among consumers.  The top three selling hybrid vehicles in March were all Toyota models -- Prius, Camry, and Lexus CT 200h. 

Of course, there was no competition for the top spot.  Toyota's Prius, which has had a stranglehold on North America's hybrid market since it was introduced, represented more than half of all hybrid sales in March with 27,800 units sold -- this is more than five times the number of sales compared to the next most popular hybrid, the Toyota Camry (5,404 units sold).

The most popular domestic hybrid was Chevy's new Malibu Hybrid which ranked fifth in sales with 1,416 models driven off the lot.  The Ford Escape hybrid, meanwhile, saw its consumer value drop significantly in March.  Only 162 Escape hybrids were sold, representing a 62.7% drop in sales compared to February, the most significant drop in the market.  In 2012, Ford has seen the Escape's sales drop more than 62% compared to 2011.

Although still representing a mere fraction all vehicle sales, plug-in electric cars also saw significant growth in March.  4,161 electric vehicles were purchased last month, compared to 1,662 in February.  This exponential growth isn't just a flash in the pan either, sales of plug-in vehicles are up a whopping 323% in 2012 compared to 2011.

Much to the chagrin of Newt Gingrich, the Chevy Volt, a plug-in hybrid, represented the most popular plug-in vehicle with 2,289 sales, more than half of all electric vehicle sales in March.  The Nissan Leaf, an all-electric vehicle, considered the Volt's largest competitor in America's nascent plug-in market finished with 579 sales, placing it third in terms of sales, and well behind the Volt.

Even though there doesn't appear to be much of a competition between the two vehicles, the Leaf's sales in March were a 21.1% increase compared to February.  Furthermore, as electric charging stations become more prevalent and the infrastructure for EVs increases, the Leaf could very well close the gap with the Volt.  And, despite its sales growth in March, the Chevy Volt's future is very tenuous, as GM announced in March that it was halting production of the vehicle for five weeks because of slow sales.

Not to be forgotten in the plug-in market, Toyota jumped on to the scene with the release of its plug-in hybrid version of the Prius. In its first month on the market, the Prius PHV sold 911 units, placing it as the second most popular plug-in vehicle.  The Prius may be poised to own another market.

Lastly, clean diesel vehicles saw their sales increase in March, too. Clean diesel vehicles burn ultra-low-sulfur-diesel, which emits 97% less sulfur.  Additionally, clean diesels are equipped with exhaust treatment systems capable of further reducing emissions.  Not surprisingly, European manufacturers dominate this market. 

The most popular clean diesel model in the United States is the Volkswagen Jetta.  In March, 5,047 Jettas were purchased, representing nearly half of all clean diesel sales.  In fact, through sales of the Jetta, Passat, and Golf, Volkswagen represented nearly 80% of clean diesel sales in the U.S.