All those LPG lovers are proved pretty much right in this months Evo. They did a test with 6 cars, 3 were diesels (Mini Cooper D, BMW 123d and Alpina D3 Bi-turbo), 2 were small engined petrol (Smart ForTwo Brabus and Panda
100hp) and one was an LPG'd Megane 225 (2.0 16v Petrol Turbo). They mentioned the cost of the conversion etc and show if you do 12k a year, it would take you 18 months to get the costs back.Anyway, the test was an economical 200 mile motorway drive @ 70mph, followed by 100 miles of hard-driven A and B road work. They were trying to prove you could still have a sporty fun drive and be ecocomical. Over the 300 miles combined, the Megane only made 24.56mpg - but was only 10.06p per mile, which was the cheapest. The others made between 40 to 50 mpg and cost between 11.8 and 14.79p per mile. So with a thirsty standard motor, LPG still won, imagine if they'd used an LPG'd Panda 100 heh!
I thought it was about as interesting as anything to do with MPG and LPG could be anyway hehe :-)