Different fuel types suit different driving styles, as well as being more or less environmentally friendly.

Petrol

Petrol is a better choice than diesel if you are mainly driving in urban areas, because of reduced particulates (although some would argue this is outweighed by less efficiency in a cold petrol engine during short journeys). It should be fitted with a catalytic converter (as all new cars built since 1994 are).

Generally speaking, petrol engines are less efficient than diesel, and produce more CO₂, CO and hydrocarbons.

Make sure you are buying ultra low sulphur petrol, as this reduces emissions and improves the efficiency of newer exhaust catalysts. Look out for zero sulphur fuel, coming soon.

Diesel

Diesel is better than petrol for long-distance driving. However it produces more black smoke and particulates, which are a problem in cities, as well as more nitrogen oxides and sulphur. Diesel is denser than petrol and produces more energy per litre. There can be up to 40% less CO₂ emissions from a diesel engine compared to an equivalent petrol engine.

Check that a diesel vehicle has a particulate trap, which can reduce emission of particulates by up to 95%.

In addition, an oxidation catalyst, now fitted to all new diesels, can reduce exhaust pollutants by half.

You can pay up to £1000 more for a similar diesel vehicle to its petrol equivalent – this should pay back for the average mileage driver in around 7 years.

Make sure you are buying ultra low sulphur petrol, as this reduces emissions and improves the efficiency of newer exhaust catalysts. Look out for zero sulphur fuel, coming soon.

Electric

An electric vehicle powered from a renewable energy source (that windmill in your garden?) is the best possible option in terms of reducing environmental impact, however, there are practical issues.

They tend to be lightweight, have poor performance, and have a limited range, perhaps around 30-60 miles between recharges, which can take 3-6 hours to complete. Batteries are large, limiting luggage space. You will need to ensure you can park close enough to a recharge point (aka a plug socket) when required. So they are only really suitable for short range urban travelling.

An electric scooter will be more expensive than a petrol equivalent, and an electric car £5,000 or more than a petrol equivalent, however running costs are much lower: as low as 1p per mile.

There are additional benefits: the G-Wiz, one of the best known electric vehicles, is exempt from road tax, has zero tax liability, requires only group 1 insurance, and is exempt from the London congestion charge. However, note recent safety concerns.

However, there is still an image problem. Perhaps not in the Clive Sinclair C5 league, but until a core of the population bite the bullet and opt for the electric vehicle as a commuting option you will still stand out from the crowd. They are not sexy. If you can’t live with that, don’t buy one.

You may have read about the PowerShift grant, available to purchase or convert cars to electric or LPG – these are no longer available.

Hybrid Vehicles

Hybrids are vehicles that are powered by both a petrol engine and an electric motor (with a battery). They work in different ways, to maximise energy efficiency. Hybrids do not require connection to an electrical supply to charge the battery: this is done by utilising “wasted” energy produced during driving and storing it in the battery.

Hybrids on the market currently include the Toyota Prius (the best seller), Honda Civic IMA, and Honda Insight. They cost more than conventional engined cars. Running costs are however around 60% of the conventional equivalent. They have the additional benefits of reduced VED, tax allowances and exemptions from the congestion charge.

LPG

Liquified Petroleum Gas (LPG) is the same fuel you find in your calor gas burner – a mixture of propane and butane. The fuel burns more efficiently and emits less CO₂ (15% less) than petrol, and produces less particulates than diesel. However CO₂ emission are greater than diesel. Also, LPG is lighter than petrol, so although weight for weight it is superior, a litre of LPG produces far less energy than a litre of petrol. Overall, expect fuel savings to be around 35% using LPG over petrol, that’s typically £300-£400 per annum.

Improvements in petrol and diesel technology mean that the benefits of using LPG are not as great as they used to be, and as a result tax breaks for vehicles using this fuel have been reduced.

It will cost you between £700 and £2,000 more to buy an LPG car than a conventional equivalent. Running costs are however lower – they can be as little as half the cost of a petrol equivalent. It costs around £2,000, and takes up to a week, to convert a car to run on LPG.

Make sure you opt for an installer which is a approved by the Liquid Petroleum Gas Association (LPGA). A full list of LPGA approved installers is provided at the Boost LPG website.

Some cars are “dual fuel”, that is they have both a petrol tank and an LPG canister

A significant amount of space is required to install the gas canisters (usually in the boot).

There are around 1300 LPG refuelling stations in the UK, listed on these websites:

Autogas

Boost LPG

Get LPG

Natural Gas

This fuel is only suitable for large vehicles such as trucks and buses, as a large on board storage tank is required. However, vehicle emissions are low and this is a good environmental choice.

Biofuels

Biofuels are fuels made from specifically grown crops such as soyabean, sunflower and oilseed rape. They are supposedly CO₂ neutral in that the same amount of CO₂ is absorbed from the atmosphere during growing as is released when the fuel is burned (although of course this does not account for the energy required to grow and process the crop, unless this comes from a renewable source). However, two separate studies in the journal Science have both concluded that crops currently used to produce biofuels release more CO₂ into the atmosphere than they absorb.

If we were to switch completely to biofuels huge areas of land would be required to grow them, which would be impractical. There are serious concerns emerging about the sustainability of this approach, and its impact on the environment, including biodiversity.

Biodiesel, now on sale in the UK, is conventional diesel mixed with a proportion of biofuel, usually around 5%. Due to tax breaks, it is cheaper than 100% diesel.

For a list of filling stations go to biodieselfillingstations

There are concerns that biodiesel may damage engines, especially if a greater than 5% mix is used.

Bioethanol/Methanol

Bioethanol is made from fermenting sugar beet and what grain (it is after all a form of alcohol – some would say a waste to burn it in an engine). It is not currently commercially available in the UK, but is used in Brazil, Germany, Sweden, Holland, and there is one pump in Iceland! It is usually mixed with conventional fuels, as is methanol, which is produced from crops as well as from natural gas and cow’s bottoms.

Cooking Oil

If you are considering modifying your car to run on cooking oil, the Low Impact Living Initiative have lots of information to help you along.

I Don’t Want to be That Radical

Practically speaking, a small manual transmission diesel is your best choice, if it is practical for your circumstances. But don't just go out and buy a brand new one - that could do even more damage to the environment.