[mjh93sa]

Difficult to use the figures I have.

For the 330d, which was run on a diet of V-Power diesel, (except for an annual trip to the Isle of Man where it was not available) running on normal Shell mpg was 37-38mpg, down from a normal 41-43mpg. But as this would have been driving around at slower speeds and up and down the Mountain it's difficult to see this as a real comparison.

Cetane rating is burn rating for diesel. Even the premium diesels don't really give a higher rate, so it's down to cleanliness and smoothness of the burn.