A requirement for ultra low sulfur diesel (ULSD)was started in 2006 (Calif) and 2007 (USA).
ULSD does 2 things for a diesel engine. First, ULSD reduces the fuel’s lubricity and tends to harm injectors. Second, the fuel burns faster without sulfur and reduces mileage 5-10%.
Also, there has been a change in injectors going to common rail as opposed to pressure directly from a pump to each injector, sequentially. The newer injectors started out being a solenoid valve, and now are piezo-electric (ref. Ford.)
What does all this mean? Well, only ultra low sulfur diesel is available, so fuel mileage will be reduced in any diesel, no matter what the year. Also, buying a newer model provides some security against the mechanical effects of ULSD through design changes. And finally, there have been some problems with common rail injectors though they are all worked out now. The Chevrolet/GMC diesel is designed by Isuzu, so it probably has a longer design history behind it. I believe Ford gets International diesels (and they were in a legal fight over warranty service,) and of course Chrysler Corp is Cummins.
I understand that a diesel truck is a pearl beyond price, but I'll stick with gas for the nonce.
Boris