We show you what to look for when buying a green car and how to get a great deal.

What to look for

There are a number of key features to look for when buying a green car.

Consider fuel economy before buying – some cars will run further on less fuel than others. Find out how many miles per gallon (MPG) the car can reach. The higher the number, the longer it’ll run on a full tank of fuel.

What fuel does it use? Some alternative fuel vehicles like electric cars may be exempt from tolls such as the London Congestion Charge.

It’s also just as important to see the car’s CO2 amount. Vehicles which emit less CO2 are cheaper to run due to lower-priced tax bands, and are better for the environment than cars which emit high levels of CO2.

New tax bands

Visit our complete 2009 car tax guide for all the revised road tax prices for April 2009 to March 2011.

To find out how much CO2 your car emits check your vehicle handbook.

Green fuels

The type of fuel your car runs on will have a great impact on your buying decision.

Hybrid

Hybrid vehicles run on a combination of fuel and electricity. Benefits include good fuel economy and low CO2 emissions, but hybrids can cost more than other green cars and engine noise is near silent around town

Usually the battery is automatically recharged by the car’s engine or from kinetic energy, absorbed when braking.

Petrol and diesel

It may be surprising to see a petrol or diesel car labelled ‘green’, but car manufacturers are always coming up with new ways to improve the fuel efficiency of petrol and diesel engines.

Diesel cars tend to have slightly better fuel consumption than petrol engines but the price of diesel at the pumps is currently higher.

Biofuel

You may have heard stories of motorists running their diesel cars on chip grease, vegetable oil – and even chocolate.

Biodiesel is made from different types of new or used oil which has been filtrated and purified. Bioethanol is produced from everyday farm crops like sugar cane. Some types of biofuel can be mixed with either petrol or diesel in flexi-fuel vehicles.

LPG

Liquefied Petroleum Gas (LPG) – or Autogas – is an alternative fuel which costs about half the price of petrol and diesel and cars emit less CO2 when powered by it.

Most engines can be converted to run on LPG, but not all – check with a UKLPGA-approved installer first - the trade association for LPG.

Electric

Some cars are powered by an electric motor which means no car tax or petrol costs, and exemptions from tolls such as the London Congestion Charge. They usually run for around 50 miles before needing a recharge, using a mains socket or special charging station.

Some are small enough to fit into cramped parking spaces, but they tend to have a low top speed of around 40-50mph, and use a lot of electricity.

Hydrogen

Hydrogen vehicles run on high-pressure fuel cells and their only emission is water vapour. Production is expensive, but after more years of research they could be a viable alternative for the future.

Making payment

If you're applying for a loan, shop around for the lowest rates. You can search over 400 loans at autotrader.co.uk – just click ‘Loans’ at the top of the page.

When seeking finance direct from a dealer, make sure you can pay off the monthly repayments. Find out how much you’ll pay back altogether – if it’s more than one and a half times the cost of the car, you may be better off looking for finance elsewhere.

Remember the more deposit you pay, the lower your monthly repayments will be.

Used car deals

Going down the used car route can be a great idea if you want a green car for less, but it may take more work than buying from new.

One of the main issues when buying a used hybrid or electric car is the condition of its battery pack. Ask the buyer about its condition before buying – a replacement can cost more than £1,000.

The estimated life expectancy of the batteries in some hybrids is more than ten years, or roughly 150,000 to 200,000 miles.

Always check the car extensively for any problems and take it for a test drive. Locate the car’s 17-digit Vehicle Identity Number (VIN) and check the V5C document against the vehicle – the numberplate, make, model and VIN should match those on the car.

Since a lot of green cars are relatively new, they hold their value well. When paying, get a signed receipt as proof of purchase. Try and pay the seller in a bank and avoid carrying around large amounts of cash. It’s a good idea to bring a friend or relative with you.

Get a car history check before buying – this will tell you if the car’s been written off, stolen, scrapped or is subject to outstanding finance. Visit vehiclecheck.co.uk.

For more advice visit autotrader.co.uk/buying.