The tests are ‘more cumbersome, and take two to three times longer than in past’.

Volkswagen Group has brought its top-selling models into line with Worldwide Harmonised Light vehicle Testing (WLTP) regulations, after the tougher rules came into force on September 1.

Reporting in Automotive News Europe says Volkswagen Group sales fell by half across the five biggest European markets, after a number of its top-selling vehicles didn’t meet emissions standards under the tough new testing procedure.

As of October 5, the best-selling variant on every Volkswagen model range is now WLTP certified.

Last month, Thomas Zahn, head of Volkswagen sales and marketing for Germany, said the new tests are “more cumbersome, and take two to three times longer than in past”.

“The coming months will be challenging for us,” he said.

The company reportedly had a stockpile of cars at its factories around Europe, and was renting space at Berlin’s unopened international airport to hold vehicles that were already sold but hadn’t met type approval under the new rules.

Deliveries for some Golf variants were subject to 14 or 15 weeks, up from six or 10. Unsurprisingly, those delays were causing significant frustration for both dealers and customers.