L - LPG
LPG (Liquefied Petroleum Gas) - This is an alternative to petrol and diesel, but is usually used in conjunction with petrol in bi-fuel cars. The LPG is housed in a separate tank in the boot and the driver is able to switch between the two sets of injectors (one for petrol, one for gas) on the move using a dash-mounted switch.
LPG gives worse economy than petrol or diesel, but pollutes less and costs much less, so it is a cheap option. LPG vehicles are also exempt from London's congestion charge. (See also Alternative fuels.)