At a works meeting held in in Wolfsburg, Volkswagen Group CEO Herbert Diess described the new fuel economy and CO2 emissions testing standard, WLTP (the Worldwide harmonised Light Vehicle Test Procedure) as a 'challenge'. He also warned of 'production interruptions' in the third quarter of this year as required type approvals under the new standard become available, with stockbuilding and halts to Wolfsburg production lines at times also expected.