We have just got back from a week in Dorset. On the way down, and including some local driving, my s type 2.7 D returned 49.2 miles to the gallon using Shell premium Diesel. On the return. the car returned 40.5 mpg using standard ESSO, but a few more [about 20] local miles.
There some roadworks on the M5 in both directions and possibly more on the return journey, but I am rather pleased with the fuel consumption.