We look at where you can convert your engine and how much it costs.

• Petrol – 120p per litre – costs £1,248 per year*
• LPG – 60p per litre – costs £624 per year*

What is LPG?

Liquid Petroleum Gas (also known as LPG or autogas) is one of the cheapest fuels available.

It also has lower CO2 emissions than petrol and LPG engines are half as noisy as diesel engines.

The mpg rate for LPG cars is around 20 per cent less than petrol. However, as LPG generally costs half the price of petrol, running your car on LPG could reduce your fuel costs by 50 PER CENT.

How to convert your engine

Converting a car to run on LPG is reasonably painless.

Choose a garage approved by the LPGA, who represent all the major LPG companies in the UK.

It costs around £1,600 to convert a petrol engine to run on LPG, but you could make this back in under a year depending on annual mileage and the size of your car.

UKLPG, the UK’s LPG trade association, showcased LPG as a cleaner and cheaper alternative to petrol at the 2008 British International Motor Show.

But not all cars can be converted to run on LPG and this service won’t be available at every garage. Check with an approved garage first.

For more information on conversions, visit our LPG Cars advice page.

Where you can fill up

You can find out where to buy LPG by viewing this list of UK refuelling stations.

View our money-saving slide show

Save money with our top ten fuel-saving tips

Does your car run on LPG? Have your say on the Auto Trader Blog

Come back tomorrow for more money-saving tips.

Disclaimer: Auto Trader cannot guarantee the above advice will always save you money.

*Annual costs are based on a fuel intake of 20 litres per week.