I bloody love all these people running to the defence of LPG motors. If it's that epic, why isn't your car LPG'd? (exception of Entwood of course).

My car is LPG, and on a long run, it is very, VERY cost effective. Short runs, just added weight to a standard car, extra money for servicing.
My argument is simple..... a cheap to run car like a 1.2 Corsa, the savings will be minimal. A thirsty 5.0 Merc, it's a no brainer.
If I ever own another Omega, it'll be (as always have been) a V6. The first thing I'll do it LPG it. I'll LPG is because it'll save me a lot of money. If I were to buy a 1.2 Corsa, 1.6 Astra, even a 2.0 Vectra, unless I had the kit in the garage, I wouldn't bother because it would be a waste of money. I wouldn't necessarily turn down the aformentioned cars if they had already been converted, but I very much doubt the tank would see gas.