Clean diesel technology offers consumers a viable alternative to gasoline using technology that has already evolved and can be further tweaked. It is fuel with an entrenched fuel infrastructure that can be substituted with bio-fuels as inventiveness blossoms.
GEO2 Technologies is one of the flowers bearing fruit by developing a ceramic composite material for use as catalyst support substrates and particulate filters for diesel engines. According to their website, the technology can reduce manufactures cost by 30% with a product that offers low back pressure and a high filtering capacity.
About half of the vehicles in Europe are diesel while the technology in the U.S. stands at about 2%. A diesel engine is about 20% more efficient than a gasoline engine. Diesel ,gallon for gallon, creates more energy.
Source:U.S. Gov. Energy Infromation
There still a cost consideration to the consumer for running gasoline over petroleum diesel which is quite substantial in some parts of the country. If there is a 45 cent per gallon cost difference between each fuel as it often is here in York, Pennsylvania, a 20% gain in efficiency is quickly eroded. There are more taxes paid at the pump for diesel, which is an attempt to extract over-the-road charges for trucking. However, the diesel will probably be simpler, cheaper and easier to maintain in a high mileage vehicle than a gasoline hybrid.
Unlike corn based ethanol production (that places pressure on food stock with a highly taxpayer subsidized fuel that takes great amounts of energy to produce a fuel that is less efficient than fossil fuels), increasing clean diesel production isn't diverting a commodity jacking up prices/inflation for consumers.
If you need more diesel, you will need less gasoline the equation on the equity market actually decreases. As a bonus the cars running diesel take 20% less fuel so less crude is needed and we become less energy dependent.
While many countries have adopted diesel as their dominant fuel due to the necessity of historically overall high energy prices, the U.S. has historically enjoyed cheap gasoline and marginalized diesel via marketing and tax structure as a working fuel (for trucks/trains/farm).
The biggest hurdle to drawing in clean diesel technology as one of our short-term Band-Aid energy solutions will be overcoming a long standing perception by consumers and bureaucrats that this is a truck fuel and shouldn't be part of the equation. Propelling an idea that doesn't create large profits for a large market force and only may benefit the consumer in the short-term isn't a market motivator.
The U.S. military wanted to streamline their fuel needs. Instead of multiple fuels for different vehicles they wanted to economize the distribution process with one fuel. 
