When choosing a vehicle, try to select one bearing in mind economy and emissions.
There are advantages and disadvantages in all types of fuel. To help you make an informed choice and understand the effect each has on the environment, some of the differences are explained below.
Petrol engines
The modern petrol engine has been designed to operate more efficiently to meet increasingly stringent emissions standards.
Key factors in this improvement in reducing exhaust pollution are
- Fuel injection
- Electronic engine management systems
- Redesigned exhaust systems.
Ever stricter controls on exhaust emissions require catalytic converters to be fitted to the exhaust system of all new petrol- engine vehicles.
Catalytic converters - these are exhaust treatment systems which remove up to 75% of carbon monoxide, nitrogen oxide and hydrocarbons.
The converter is a honeycombed filter with a total surface area about equal to a football pitch. This surface is coated with precious metals such as platinum, palladium and rhodium. These speed up a chemical reaction in the exhaust gases as the engine heats up.
The oxygen content of the exhaust is monitored and a sensor triggers controls to adjust the air-fuel mixture.
The convertor only deals with toxic and polluting gases. Carbon dioxide is still produced.
Leaded patrol cannot be used in vehicles fitted the catalytic converter. Even one thankful can permanently damage the system.
If you over-accelerate or exceed 3000 rpm the catalytic convertor cannot clean up emission completely, and will release some that are contaminated. Make sure therefore that you don't drive in such a way that this will occur.
Diesel engines
These engines are very fuel efficient and produce less carbon dioxide (a global warming gas) than any other road transport fuel.
Compared with petrol-engined cars they also emit less carbon monoxide and hydrocarbons. They do, however produce more emission oxides of nitrogen(NOx) and particulates which are bad for local air quality.
Newer vehicles have to meet strict new emissions standards aimed at reducing these pollutants , and all diesel vehicles can now use ultra-low sulphur diesel fuel reduce exhaust pollution.
New fuels
There are alternatives becoming available to the standard petrol and diesel fuels.
City Diesel and city petrol-these fuels are now available at most filling stations. They have been formulated so that the sulphur content is very low.
Sulphur is the main cause of particulates in exhaust emission, and also produces acid gases. The lower sulphur content in these fuels helps to reduce this source of pollution.
LPG (Liquid Petroleum Gas)-LPG-powered vehicles are now commercially available and the number of fuel stations is increasing steadily.
This fuel is cheaper to use than petrol or diesels and the emissions cause less air pollution. However, LPG does produce more carbon dioxide per mile travelled than diesel.
Choosing a car
Try to choose a vehicle with low fuel consumption and emissions. The Department for Transport (DfT) produce a guide about the fuel consumption of new vehicles.
Other options to bear in mind
- Cars with automatic transmission use about 10% more fuel than similar models with manual transmission.
- Consider using ultra-low sulphur petrol which is available at most filling stations.
- If you own a diesel car or van, use ultra-low sulphur fuel, such as city diesel as it reduces harmful emission of particulates.
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