had a quick read up...
seems simple enough!
gas tank in the spare wheel well, hoseing running underniethe the car to some sort of vapour tank in the engine bay (converting the liquid gas to vapour). then to some new injectors where the gas is injected straight into the engine
you also get a new ECU to go along side your exsisting ECU and a push button to tell the ECU to switch between gas and petrol.
there is adverts for these conversions as cheap as £900 but didnt look into the quality of those conversions
seems the general view is that running on the LPG you are cutting your fuel costs in half, but i guess that depends how much you use the LPG? as you have the option to switch to petrol whenever you want! which i guess can be determined by your mood/driving needs. Eco-drive, put the LPG on! in the mood to put your foot down, switch back to petrol!
couldnt really find any info on how much additional weight you get with the LPG. Also more importantly, when switching from petrol to LPG on a (quite possibly) regular basis, what effect will this have on the life span of the engine?