Phil
I have just got rid of my Vectra C 2.2DTI fantastic car for fuel returns high 40's mid 50's to the gallon. The only fault was when towing was when the engine management light would come on throwing the car into limp home mode, great fun when you are overtaking on a busy A14 on a Friday afternoon, never actually got to the bottom of the problem even after software downloads from the main stealers.
Have now swapped for a Mondeo auto TDCI far better car for handling and driving altogether although have not got round to fitting the towbar yet should be done in the next fortnight or so.