The main producer of greenhouse gases in Switzerland overall is transport, which accounted for nearly 31% of such emissions in 2000. The main gases involved are carbon dioxide (CO2) and nitrous oxide (NO2).

The Swiss produce about six tonnes of carbon emissions per head per year, of which transport is responsible for 2.6 tonnes. This compares with a total of 20 tonnes for the US, and a world average of about four.

The average car in Switzerland has a two-litre engine, compared with only 1.6 litres in neighbouring countries, according to the European Automobile Manufacturers' Association. Switzerland is considering the introduction of incentives to persuade people to buy cleaner cars.

Drivers are encouraged to turn off their engines when waiting for short periods.

The Swiss government has proposed legislation to lower taxes on fuels that produce fewer harmful emissions, and to abolish them completely on fuels from renewable resources.

Projects are underway at different Swiss research institutions to develop new, more environmentally friendly fuels.

Traditional vehicle fuels

Ever stiffer legislation has been introduced since the 1970s governing the lead content of petrol (gasoline) and the sulphur content of diesel.

Nearly 30% of new cars in Switzerland are diesel powered. The number of diesel cars on Swiss roads trebled between 1990 and 2005. In order to combat air pollution, Switzerland wants all new diesel vehicles to be fitted with particle filters as of 2007.

However, the government has been criticised for not being stricter and for not setting a good example. Some 16,000 army diesel trucks were still on the road in 2006 without filters.