In the UK petrol (sorry gas) is expensive (92pence/litre). Hence I decided to have it converted. In short here's how it goes. A separate tank is fitted in the vehicle (in my case under the vehicle) to hold the pressurised lpg. A injection system is fitted in addition to the factory system with its own 'Brain'. The vehicle then switches automatically from gas to lpg when the engine temp. reaches the required temp. When the lpg runs out the system switches back to gas. No need to stop the car or anything like that. Regarding your question about mileages. LPG (Propane) is weaker than petrol in terms of energy output when combusted hence there is a drop of upto 20% in miles/litre. Also they claim that there is a slight drop in BHP. However this doesn't really show on a large vehicle such as the ML.I'm getting 18miles to the gallon (UK gallon, 5L=1.1gal).Conversion cost Ã‚Â£1600. LPG is 32-40pence/L. Was 26p until the recent global oil price hikes.I think this is not suitable for the US market as your fuel is reasonably priced. Let me know how much LPG costs over there.
Before you ask, I will post some images of the conversion.
Converted to dual fuel. LPG.