if every car had a fuel computer in £ and pence it would save a fortune
some people think they are being efficient (my wife) but are way off, i used to leave my cars on ave con and try to get absolute maximum fuel savings, the next day 'd be flat out everywhere mind but all that practise made me good at what saves fuel
its not aboutbeing slow and holding everyone up, i give it poke to get to cruising speed and let it run freely, 1.6 16v scenic currently giving ave 41.3 mpg on this tank
my '10 transit gets 500 miles to a £95 tank full tho