My new Superb had a baptism of fire this weekend, enjoying it's first 350 miles loaded to the hilt with it's enormous boot crammed full of our camping gear and the whole family on board and the tank brimmed.   Driving with no regard for economy, suffering traffic jams, comfort breaks and driving at the speed limit - all with a fresh and tight engine, I was very impressed with 65.4 mpg...     Which then left me wondering what it was actually capable of when lightly loaded, driving with max