I cant speak for your common rail.. but I can speak for every single other gas car, and my 2 diesel trucks and my diesel car.. with standard transmissions, running the rpms up (in a diesel) to about 2k or so, or longer on hills, is the best for mileage. Diesels do NOT like being short shifted.
What I've noticed with all of my autos though, is the lighter on the throttle, the better the mileage. Now keep in mind, every single car, truck and motor are different. But "typically", standards like more rpms, and autos like being shifted early.
I know that people with tdi Volkswagens get 70+miles per gallon leaving their cars in 4th gear on highway runs (Can you say 3500-4k rpms in a diesel?). Not good at ALL for the rotating assembly.. but great for mileage.