LPG stands for Liquid Petroleum Gas and is a convenient energy source for a lot of different purposes which include cooking and heating as well as being a fuel for vehicles. LPG is also referred to as Autogas. LPG is a hydrocarbon fuel which is comprised of mostly propane and butane. The gas is liquefied under moderate pressure and when allowed to revert to vapour it then expands to 270 times its liquid volume. Converting your vehicle to LPG can be costly to convert, around $3000 - $4500. The advantages to using LPG as your motor fuel is that it can be up to 60 percent cheaper than the cost of petrol per litre. Also the vehicle will give out fewer exhaust emissions and increase the life of the engine. What does an conversion to LPG involve? First of all an LPG storage tank will be installed in the vehicle. This usually will go in the boot of the vehicle but if there is enough clearance this can go under the floor, this usually will only happen on 4WDs and a few commercial vehicles. The tank is fitted with an (AFL) Automatic Fill Limiter. This means that you cannot fill the tank past the safe fill limit of 80 percent. This is to ensure there is enough room as LPG expands with changes in temperature. A regulator or converter is then added. This will convert the liquid gas into a gaseous vapour and also to regulate the process. After this a special air-fuel mixer is then installed, this ensures that the correct amounts are mixed together so to give proper combustion. A fuel lock is fitted next that allows the fuel to flow when the engine is running but will shut off the supply whenever the engine stops running. Some vehicles have dual-fuel which are able to run on either one of two fuels, which is usually petrol or LPG. It would not cost any extra to have the vehicle converted to dual-fuel than it would to convert it to run on LPG only. Making the vehicle dual-fuel would give more flexibility. Not all vehicles can be converted to LPG or dual-fuel. Some do not have a conversion kit for that particular vehicle. For some vehicles it may just be that there is not enough space for the LPG cylinder or that there is durability problems with the engine or it could be that the manufacturer of the vehicle does not know if the vehicle is compatible. If you do convert your vehicle to LPG or dual-fuel you should ask about any additional servicing or maintenance that needs to be done above the vehicles requirements. If car rental companies in major cities, like Sydney do start to move their fleets to vehicles which run on LPG or dual-fuel then this would reduce their carbon footprint as well as helping to reduce their costs for refuelling their fleets. This would also reduce the cost for car rental in Sydney.