What fuel

The next time you're in the position of buying a new or used car, one thing to keep in mind is what type of fuel your new motor will be using. The type of fuel it uses can have many different impacts on your driving experience. Which emissions regulations being updated and changed all the time, and newer and more efficient engines coming to market each year, the choices you took last time you bought a car may not be the optimal choices this time round.

Ever more stringent guidelines are coming in to govern the amount of particulates that engines can legally emit, with EU regulations targeting anything that may cause breathing problems in our congested cities. In order to meet new regulations, newer cars are equipped with extra kit to reduce emissions as much as possible. However, every time more equipment is crammed into a car the price goes up, and the emissions control technology can also impact performance on various types of usage.

Diesel

In the past, for people usually taking short journeys, diesel engines were recommended due to efficient working of the engine during initial sections of a journey. However, now new diesel cars usually come fitted with diesel particulate filters (DPF), and are now better suited to longer journeys. These filters can give up to 80% reduction in particulate emissions, but without regular running at a high engine speed these filters can get clogged. The stop/start urban drive that used to be great for diesels has now been replaced with long motorway journeys for newer cars.

Petrol

Diesel engines aren't the only ones to see reductions in emissions. A number of manufacturers are using the 'lean burn' method to burn more fuel and emit less particles. This method involves using more air particles in the engine. This is often coupled with fuel injection systems in an attempt to help increase the fuel economy of the vehicle. However, as these 'lean burn' engines often burn at a higher temperature than usual, additional nitrogen oxide is produced, and thus NOx traps have to be fitted to vehicles.

These lean burn engines are efficient at mid to high level speeds, especially on motorway journeys, but on urban runs much less so. The lower the speed of the engine, the less chance it is able to take advantage of any lean burn tech, and so for short journeys any fuel economy advantage is lost.

Making the choice between petrol and diesel

You will on the whole pay less for a petrol powered car, however a diesel vehicle will hold more of it's value when selling it second hand. The cost of maintenance and servicing for a petrol car is comparable to a diesel one, and both will require a similar level of servicing every year. Nowadays a vehicle's car tax is worked out from it's emissions of CO2 gasses, and as diesel engines are more efficient in this respect, the cost of taxing your diesel car will be less.

If you're mainly a motorway driver and cover a large distance in your weekly travels, your best bet may be a newer diesel, fitted with a DPF. This will give you good fuel economy, better resale value, and your filters should stay good and healthy. If you're mainly taking short local trips as the bulk of your driving, then a smaller engined petrol car, without fuel injection or a lean burner, will suit you best. If you're opting for a diesel, and it's a second hand vehicle, you should it's date of first registration. If it was registered in 2005 or above, there is a good chance that a DPF is fitted.

Biofuel

Biofuel is now present in all consumer petrol and diesel. Petrol contains about 5 percent ethanol currently, and this amount is due to double in the near future, whilst diesel contains about 7 percent biodiesel. Whilst some engines will cope with a higher level of biofuels, you should check with your car's manufacturer of the correct levels to use, or alternatively you can have your engines modified to accept a higher level of such fuel.

LPG gas

Liquefied petroleum gas is a mixture of hydrocarbon gasses and is a by-product of the refining process used on crude oil. It is available for a lower price than diesel or petrol, as much as half their normal costs, though yields about a quarter less fuel economy. It is thought that after engine conversion costs, an LPG-powered vehicle can cost around 30 percent less than a petrol-powered one.

Conversion costs of around £2,000 will cover the work needed to upgrade a petrol car so it can utilise LPG as well as petrol, so this option is often only economical if you travel above the average miles per year. A clean burn makes an LPG-powered vehicle great for urban usage, though some car parks have restrictions on them, and services such as the Eurotunnel will not allow them. You should always make sure any conversion work is done by a respected mechanic.

Hybrid vehicles

Numerous hybrid vehicles are now available on the market, such as the famous Toyota Prius. These cars have both an petrol engine and an electric motor, coupled with an on-board battery. When the vehicle goes through stop/start urban driving conditions, the battery for the electric engine gets charged by the petrol engine. The braking process also helps to charge the battery too, by turning the kinetic engine into an electric charge. Usual brakes just produce heat energy, which is wasted. When the hybrid vehicle goes at high speed, this is when the electric motor kicks in to support the petrol engine.

Because of this, hybrids are great for urban driving and getting around town, though if you're mostly a motorway driver you won't see decent fuel economy - stick to the diesels for that.

Electric vehicles

Like hybrids, electric cars are great for urban driving, and in addition they produce no emissions, and thus are tax exempt. However, range is rather limited, and they are not as easy or indeed quick to refuel as conventional vehicles. Recharge station facilities are becoming more widespread, but the bulk of them are still in the London and South East England area.

Should you be thinking of purchasing an electric vehicle, you should spend a good amount of time on the test drive, as it may take a while to get used to limited ranges and the mechanics of recharging the car, especially if you're used to petrol vehicles.