The EPA does not want diesel powered passenger vehicles in the US, period, and it has nothing to do with emissions. The diesels used throughout the world today are nothing like the big three cobbled together engines of the 70’s and 80’s. If allowing for gains in thermal and volumetric efficiency of current engine designs, combined with body, chassis, and powertrain improvements, 60 MPG gas and 80 MPG diesel mid sized vehicles should have been on the market around the late 90’s. That isn’t going to happen though, because of the influence of the oil, auto, and enviroment lobbies. I worked in the auto industry for two decades, and amongst the engineers and technicians was a collective WTF are the these people thinking? it has nothing to do with fuel economy or emissions, and everything to do with extracting as much money as possible from consumers.
Another reason why diesel fuel will require a long time to adopt is that the refineries in the United States are optimized for the production of gasoline, not diesel. It will take decades to rebuild refineries that are optimized for the production of diesel - if the environmentalists even allow it. European refineries, on the other hand, are optimized for the production of diesel.
I too spend sometime in auto and support, for a bit. I was told in the late 70's and the Diesel Rabbit showing up in the Michigan Marketplace, Diesel prices missttterriousllly went up quite a bit... Hmmm what a cowinkadink...
BTW IMHO Smart money is on CNG.
Do some research on the recent DOE type project, of going the next step with our current CNG infrastructure, i.e. natural gas to our homes. A low-cost low pressure pump and a normally shaped tank that holds 30% more than it is supposed too via nano-tech and other lung type internal absorbent materials @ a lower pressure is the goal. If they do it IMHO it is a game changer...
go here: http://www.greencarcongress.com/2012/07/move-20120712.html