Alternative fuel

Diesel

Diesel cars emit less CO₂ than their petrol equivalents, but they produce more 'air quality' emissions, such as nitrogen oxides (NOx) and particulates, which pollute towns and cities, and affect our health. If you are considering buying a diesel car, choose one with a diesel particulate filter (DPF), as this will reduce particulate matter emissions. These filters are available for many different car models, although you may have to request one as an optional extra.

Hybrid Vehicles

Hybrid cars have a conventional engine in addition to an electrical motor and battery which is recharged while you drive. Current models run on petrol and electricity, although diesel/electric hybrid models are expected soon. Hybrid cars are already available from several manufacturers and are proving increasingly popular.

Electric Vehicles

Electric vehicles produce no exhaust emissions and are exempt from road tax. You recharge them by plugging them into the mains via a normal mains socket. Most have a range of about 40-50 miles and a top speed of about 50mph, so are best suited to urban driving. However, new designs are being developed that have a far greater range. Even if an electric vehicle is not a practical option for your main car, it may be worth considering as a second car.

Biodiesel

Produced from plants, or less commonly from waste cooking oil, biodiesel is a diesel substitute that reduces overall CO ₂ emissions. The government has said that by 2010 all diesel sold in the UK will contain 5 per cent biodiesel. All diesel cars can run on B5 (a blend of 5 per cent biodiesel and 95 per cent conventional diesel). Using blends of more than 5 per cent biodiesel invalidates most cars' warranties so check with your manufacturer before trying it. You should not use untreated plant oil as this could damage your engine.

Bioethanol

Produced by fermenting plant material, bioethanol is a petrol substitute that, when used, reduces overall CO ₂ emissions. All petrol cars can run on E5 (a ready mixed blend of 5 per cent bioethanol and 95 per cent petrol). You should only use blends of more than five per cent if your car has been specifically designed to run on ethanol.

Liquefied petroleum gas (LPG)

LPG is a blend of propane and butane produced either as a by-product of oil-refining, or from natural gas (methane) fields. Vehicles that use LPG perform just like petrol vehicles. They produce approximately 10 per cent less carbon dioxide emissions than an equivalent petrol vehicle, but about 10% more carbon dioxide than an equivalent diesel vehicle. As very low emission diesel engines become more prevalent, this is rising to 15% or more. LPG also delivers up to 80 per cent lower NOx emissions than diesel, as well as zero particulate emissions.

You can convert an existing petrol engine to run on LPG - this will typically cost £1,500 - £2,200 including VAT depending on the vehicle type. Conversions are dangerous if not done correctly, so you should only use an installer approved by UKLPG (formerly the LPG Association).

Some car manufacturers have approved conversions.