London set to declare war on diesel

London looks set to declare war on the diesel-engined car if plans by Mayor Boris Johnson get the go-ahead. Under the current congestion-charge legislation, cars emitting more than 75g/km of carbon dioxide (effectively everything bar electric cars and the cleanest of hybrids) have to pay £11.50 to enter the city centre for a day.

Matthew Pencharz, environmental adviser to the mayor's office, has been quoted as saying that "over recent years the Euro diesel engine standards have not delivered the emission savings expected, yet governments have been incentivising us to buy them. This has left us with a generation of dirty diesels."

If the increase for diesel cars goes through, it is expected that Johnson would also lobby the British government to simultaneously increase the vehicle excise duty rate (the UK equivalent of our vehicle registration tax) for diesel cars, to give a greater push towards clean-running petrol engines. Petrol cars from before 2006 would also be required to pay the extra levy.

London, along with many other large cities, suffers serious air-quality issues, and the city's managers have recently come in for harsh criticism following reports that nitrogen dioxide (NO2) levels were higher in London than in any other European city. The NO2 level measured on Marylebone Road, a major route through west London, was more than twice the permitted EU maximum. Diesel engines are cited as a major source of NO2.

The plan as it stands would not affect cars with diesel engines that conform to the latest stringent EU6 emissions laws but would affect older models. This has led the AA in the UK to come out against the proposal. Its president, Edmund King, said: "Very few cars enter central London, so these measures will have more effect on the growing numbers of small businesses and service vehicles on whom London's economy relies. They will have to plan ahead to change their vehicles if they are to stay in business."

The plan could also have a serious impact on the future of diesel-car development. About a tenth of the UK’s total car population is to be found in the London area, and if diesel sales take a nosedive there the ripples could be significant.