The European Commission has tightened the WLTP test regime for new cars sold in the bloc after claims that automakers were gaming the tests.
The updated regulation, which came into force in February, requires automakers to switch on all emissions-saving technology, such as the stop-start function, and use the same driver-selectable modes for each model tested, for example Eco mode instead of Sport mode.
The Commission discovered that automakers were turning on functions during tests that increased emissions in the runup to the introduction of WLTP testing on Sept. 1, the green pressure group Transport and Environment said.
The Commission found that some automakers were manipulating tests to burn more fuel and increase emissions with methods such as switching off the start-stop function in cars being tested, adjusting the gear-shift patterns, using the Sport instead of Eco mode, T&E said.
By artificially increasing their CO2 emissions now, automakers hoped to weaken future reduction targets, T&E said.
The manipulation partly explains why there is a huge disparity in average emissions between different automakers, T&E said.
CO2 emissions increased when homologation tests in Europe switched to WLTP from the former NEDC homologation regime. The range of the increases was between 1 percent to 81 percent depending on the automaker, T&E said. It did not name the brands.
ACEA, the body representing automakers selling cars in Europe, welcomed the rule tightening.
The changes make the WLTP testing procedure "even more robust and to prevent any test manipulation," ACEA said in a statement.