I don't know, 30%-40% better mileage than gasoline and more payload, technology, space and creature comforts over the Ram that is selling well. Once fuel prices begin to go back up, they will sell very well. Ford should have done this a long time ago.
I'm currently living in Belgium at the moment and I'm guessing 70%-80 of the passenger vehicles over here are diesel. Diesel fuel is 20% cheaper, and when you are paying $5-6 a gallon for gasoline, making the switch to diesel is a no brainer. Lower fuel bills and longer times between re-fueling are always good.
Adam