The EPA has been working on "Clean Diesel" implementation over the last 6 years or so. http://www.epa.gov/cleandiesel/
We all know that Diesels are efficient, but have a problem with increased emissions in the NOx and Particulate Matter (soot) categories -- which are quite harmful to the respiratory health of anyone who breathes the tailpipe emissions.
After digging around the EPA website, I came across a collaberative effort with the International Truck and Engine Company. The following chart is adapted from their online brochure on Clean Diesel Technology (which can be found at http://www.greendieseltechnology.com...re_2004_r2.pdf
Why are we wasting our time with Ethanol? The infrastructure is there to manufacture, distribute, store, and dispense ultra low sulphur diesel (ULSD) fuel and cut our emissions, while improving our fuel economy in not only the commercial side of the biz, but potentially for passenger cars as well.
The website http://www.greendieseltechnology.com/
also has an interesting piece on the Hydraulic Hybrid UPS Delivery Vehicle prototype.
At any rate, big changes are to take place with the way the diesel engine operates past the year 2007. So, would the general North American public embrace diesel?