Fuel duels - Gas

As used in: A few Vauxhall and Volvo models.

What is it? Modified cars can run on liquefied petroleum gas (LPG) or compressed natural gas (CNG).

Cost 41.9p per litre (LPG).

Where can I buy it? At about 1400 fuel stations across the UK.

Pros: The cost of gas is low and it has lower emissions of carbon dioxide and hydrocarbons than petrol and fewer particulates than diesel.

Cons: To date, there is relatively limited supply in UK. It must be stored in
high-pressure tanks and has poorer mpg. Government grants for gas-run cars are no longer available.

Expert view: Gas is not taking off as quickly as the Government would like, but still a viable alternative.

Outlook: Needs further commitment from Government and car makers for it to catch on. Like petrol and diesel, however, LPG and CNG are finite resources.