US to toughen auto emission tests

US environmental regulators on Friday announced tighter and broader auto emissions tests to detect "defeat" devices in all cars and light trucks in the US and Canada, including gasoline engines, after Volkswagen admitted it cheated on diesel emissions.

The Environmental Protection Agency notified auto manufacturers in a letter saying authorities could require additional tests for "any vehicle" to determine whether it meets emission standards under normal road conditions, not just at controlled testing facilities.

The change could mean higher costs for automakers, particularly any that become subject to recalls or production changes, as well as bigger regulatory hurdles in obtaining certification that vehicles meet North American emissions standards.

Additional tests will look not only for nitrogen oxide emissions linked to smog and acid rain, but also for carbon dioxide, a primary greenhouse gas emitted by gasoline and diesel engines that is a proxy for a vehicle's fuel efficiency.

European regulators on Friday promised separately to show "zero tolerance" for cheating on emissions tests as European Union lawmakers pushed for tougher, real-world testing of vehicles.