As the benefits of converting to liquid petroleum gas (LPG) speak for themselves, the next step for any vehicle owner is to ascertain whether or not their vehicle can be converted to LPG, and how easy it will be to accomplish. As a rule the majority of standard cars can be converted (almost all four-stroke engine types are suitable for conversion). Vans are also easily switched over, though the process tends to be slightly more expensive simply because the storage tank for the LPG needs to be larger to meet the demands of the heavier vehicle for fuel.
Perhaps the easiest way to begin investigating the possibility of converting your vehicle to LPG is to take your car to your nearest accredited mechanic. In the United Kingdom the Liquid Petroleum Gas Association's (LPGA) quality assurance scheme maintains a register of certified LPG conversion mechanics, providing the best place to start the search.
Although you could certainly attempt the conversion yourself - there are do-it-yourself kits available - the various health and safety risks involved in the use of a vehicle fitted with an uncertified LPG conversion mean that the majority of vehicle insurers will refuse to insure your car unless the conversion has been undertaken by one of the LPGA's accredited mechanics. The LPGA will issue a certificate that verifies the quality of the LPG conversion undertaken on your vehicle so that insurance is easily organized.
It is also important that you obtain a warranty (for the procedure and the parts, or at the very least for the parts only) from the mechanic who undertakes the conversion as the LPG switch-over procedure is not covered on the vehicle manufacturer's warranty.
At present there are three different types of LPG fuel fittings that can be used in vehicles. The most common also happens to be the oldest - the converter-and-mixer system. This system converts the LPG in its liquid form into a vapour and then mixes it with intake air that is fed into the engine. The second type, the vapour-phase-injection model, is similar to the converter-and-mixer but relies upon a computer to monitor and moderate the flow of the fuel into the engine, thus improving efficiency and reducing engine strain. Most recently a third type has been implemented - the liquid-phase-injection type - which is similar to petrol injection engines in that it uses a fuel-rail for administering the fuel. Liquid-phase-injection is far more efficient than the other two types, but is not yet as readily available as its older relatives.
The conversion process uses a filler (where the LPG is pumped into the vehicle from the bowser), several hoses (the fill-hose from filler to tank, the service line from tank to converter, and the vapour-hose from converter to mixer), and a converter that warms the LPG to vapour form. The LPG tank is usually installed in the boot of the vehicle, with the petrol tank being retained. This effectively means that both LPG and petrol can be used in LPG-converted cars.