LPG stands for Liquefied Petroleum Gas, when used as a road fuel it is often known as Autogas. It is the third mainstream fuel for vehicles and is a cheaper alternative to petrol. LPG is a natural gas resource and is also a by-product of oil production. At atmospheric pressure it is a vapour, under modest pressure it becomes liquid.

When used as a fuel in spark ignition vehicles, i.e. petrol engines, Liquefied Petroleum Gas is usually branded as Autogas, Motorgas or LPG.

It is the same as commercial propane, available in red bottles for heating etc. and is around 94% propane, 4% butane and 2% other petroleum by-products. It will offer a performance comparable to petrol, in top-end speed, acceleration and refill times.

The calorific value of gas is slightly greater than petrol but the density is around 15% less than petrol. Using it as an automotive fuel to replace petrol will result in a comparable drop in MPG, BUT this will be more than compensated for as the average price of LPG is less than half the cost of petrol, resulting in half cost motoring.

Normally when a vehicle is converted to LPG the petrol system remains intact so that it can be used on either fuel thus providing an increased driving range on dual fuel where necessary.

The other major advantage is a large reduction in emissions.