As with Daimler's Mercedes, Volkswagen deliveries in September were affected by the WLTP changeover, as expected, the automaker said.
VW September sales worldwide fell 18.3% year on year to 485,000 vehicles.
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The WLTP changeover in Europe and especially in Germany, saw deliveries plunge 42.6% and 47.1% respectively.
The year to date tally nonetheless was 2.9% higher at 4,622,900 vehicles.
Sales chief Juergen Stackmann said: "Developments in September were a setback but we had been expecting this following the records in the summer. October will also be affected by the changeover to the WLTP test procedure. Currently, we have obtained WLTP approval for high-volume variants of all 14 Volkswagen brand models. By the end of the year, the changeover should have been virtually completed. From November, we will be ready for the end-of-the-year sprint in Europe."
VW said the introduction of the new WLTP test procedure on 1 September led many customers in western European markets to bring forward their purchasing decisions, resulting in "extraordinary growth" in delivery figures over the summer months and now, as expected, to the severe falls in September. Region sales were up 5.9% to 1,353,200 vehicles from January to September.
German sales fell 47.1% last month to 23,300 units but YTD was still 4.9% up at 419,200.
Deliveries in North America were 8.8% down to 49,000 in September with US sales off 4.8% to 30,600.
South America sales rose 2.1% to 38,000 with Brazil up 26.1% to 28,900.
China sales fell 10.5% to 277,800 due to "general uncertainty" among consumers in the country as a result of the continuing tariff dispute with the US.
January to September sales rose 1.9% to 2,241,300.
