IMO the problem with diesel emission regs is the refusal of the US to adopt European standards or vice versa. One standard would reduce costs and increase options in the US, with increased fuel economy as a benefit.

We have Sprinters at work. They run a looonng time on a tank. One with a box on it would be sooooo much cheaper to run than the E350 based box trucks we have that have 460s in them and get 8 to 11 mpg. Maybe soon, they say they are buying 4500 next year. Too bad Ford isn't getting a piece of it....