If you wanted further proof that eco-friendly vehicles are increasing in popularity, just take a look at the results of Challenge X, an engineering competition that seeks to find the next big thing in green cars. More specifically, clean diesel technology seems to be leading the pack for a greener driving future. The top three vehicles in the competition are diesel-powered, and 12 out of the 17 entries used the fuel.

The winners were announced yesterday at the Smithsonian Institution in Washington, D.C and were chosen out of entries submitted by the 17 participating university engineering teams. The challenge requires the teams to reconfigure a Chevrolet Equinox SUV to run using less fuel that is also made from renewable resources. The teams are able to use technology such as hybrid, plug-in or fuel cells and biodiesel, ethanol and hydrogen as alternative sources of fuel. The competition was sponsored by General Motors and the U.S. Department of Energy among others.

"Today we have a glimpse of the leading technologies that will power our future cars, trucks and SUVs, and it's no surprise that the winner was a clean diesel engine running on renewable biofuels, coupled with a hybrid powertrain," said Allen Schaeffer, executive director of the Diesel Technology Forum. "Challenge X demonstrates that, thanks to its energy efficiency and low CO2 emissions, clean diesel will play a far greater role in reducing our dependence on foreign oil and reduce greenhouse gas emissions in the years ahead. Over the next 16 months, more than a dozen new clean diesel vehicles will be available to consumers."

Mississippi State University won the competition for the second consecutive year with their through-the-road parallel hybrid electric vehicle featuring a direct injection turbo diesel engine that uses biofuel. The team increased the fuel economy of their vehicle by 38 per cent.

» The Auto Channel