Clean Diesel Technologies, a company that makes catalysts, purification systems and other technologies to reduce pollution from diesel engines, stepped off the bulletin board and onto the Nasdaq Wednesday.

The Stamford, Conn.-based company, with international headquarters in Whyteleafe, England, also said its shares will continue to trade on London's AIM and Frankfurt's Xetra.

The news that Clean Diesel would be making it's Nasdaq debut helped push the New Energy Fund, a hedge fund of global sustainable-energy stocks, up 1.87 percent Tuesday (see IN BRIEF: Energy Fund Rises, Clean Diesel Debuts on Nasdaq).

But so far, the company's stock is experiencing a rocky start on the Nasdaq. Clean Diesel shares shot up 2.86 percent, or $0.50, during morning trading to $18 from its $17.50 opening price. Around noon, the company's stock took a 20 percent nosedive, or $3.50, to $14.

Still, Clean Diesel's move to the Nasdaq highlights the growing interest in such technology. It's no secret that diesel fuel packs a higher-energy content punch than gasoline, resulting in a 30 percent increase in fuel economy.

But diesel's dirty reputation, along with strict clean-air standards, have kept U.S. drivers from purchasing diesel vehicles. America's diesel market share is estimated to reach 4 percent by the end of the year, according to Global Insight.

However, that could change as automakers bring to market what are called "clean diesel" vehicles, where treatment systems and filters cut smog-causing emissions.

"The real start will be in the 2009, 2010 timeframe when we really see these things filter in, in some volume," said Paul Lacy, technical research manager for" target="_blank">Global Insight.

Those planning to bring clean-diesel vehicles to all 50 states include the likes of Mercedes-Benz, Volkswagen, Nissan, and Honda.