My S Type had an average fuel consumption of 38MPG recorded on the trip computer when I bought her but since I zeroed it, my best is 29MPG. Maybe it will increment slowly over time :) Mind you, I also note that the coolant temp doesn't get to optimal by the time I get to work, a journey of some 10 miles mostly at 60 to 70 mph, so, even allowing for the sheer size of the engine, I might have to consider looking at the operation of the thermostat. As an adjunct, I use bog standard Sainsburys diesel rather than the branded stuff. Some say that it makes a difference. Also, I used to use Millers Power Plus additive in my fuel when I had my Rover 75 diesel. Does anybody use that in their S Type and does it make a difference please?