Drivers are turning to smaller cars, hybrids and clean diesels at levels never before seen.

The combination of ULSD with advanced emission control technologies is sometimes called "clean diesel."

A report by the California Energy Commission recently recommended blending the cleaner diesel with existing fuel stocks to meet stringent fuel standards.

As cleaner diesels emerge, the proposal becomes more attractive.

Natural-gas buses emit up to 90 percent less particulate soot than even the cleanest diesels available.

Europe lags some way behind the US in demanding clean diesels, and agriculture is down the timeline from trucks.

VW is working on an even cleaner and more efficient diesel, as well as a particle filter that, unlike current ones, does not have to be regularly changed.

Existing regulations also could be expanded to increase the use of clean diesel and clean coal technologies and to develop second-generation technologies.

"Blue skies for our children" has been their guideline in developing future vehicles, inspiring them to launch further research into clean diesels and hydrogen power.

We know that the refiners already have refineries producing clean diesel, but not for Europe. For the United States and Japan.