Hi, I was wondering what sort of mpg I should be getting on lpg. On £ 5:20 of lpg (= to 1 gallon of unleaded at £1:19lt at the pumps) and round town driving I'm getting an average 23.2 miles on a 1997 3.9 auto with just 70,000 on clock. ( just had new plugs, leads oil and filter and has K&N...