British Trade Group Defends Diesels

The U.K.'s Society of Motor Manufacturers and Traders is leading a campaign to combat movements that seek to "demonize" and ban diesel engines.

SMMT, along with BMW, Ford and Jaguar Land Rover, contend that modern "clean" diesels make worries about pollution from such engines obsolete.

Ironically, governments have for years encouraged consumers to buy diesel-powered cars, which are more fuel efficient and emit less carbon dioxide than comparable gasoline engines. But diesel also emit more oxides of nitrogen, which have been linked to respiratory problems. NOx has become a rallying point for environmentalists.

Last December Paris proposed an outright ban on all diesel-powered vehicles in the city by 2020. Environmentalists have called for similar measures in the U.K. and elsewhere.

Diesel backers point out that Euro 6 emission standards dramatically narrow the NOx emission gap. Between 2000 and this year, for example, allowable NOx emissions for gasoline engines in Europe have dropped from 250 mg/km to 60 mg/km. Over the same period, the NOx limit for diesels has plunged from 500 mg/km to 80 mg/km.

Environmentalists acknowledge the advancements for new diesel-powered cars. But they point out that most diesels on the road have older technology and emit 2-3 times as much NOx as gasoline-powered vehicles.