Mercedes-Benz sold 477,378 cars in the first quarter of 2020, down 14.9% year on year.
The switch to battery-electric models only saw Smart plunge 78.3% to 5,863 units.
Vans notched up 64,588 sales, down 14.9%.
"The pandemic developments in Europe and US and the consequences of the temporary closures of retail businesses in those markets had a significant impact on unit sales in March, Daimler said.
"2020 started well and we were able to increase sales of our core model series especially in January. The impact of the corona crisis seriously weakened our unit sales in March and we therefore did not achieve our target numbers in the first quarter," said Marcus Breitschwerdt, head of Mercedes-Benz Vans.
Europe Q1 sales fell 15.9% to 188,963 vehicles with German volume off 8.8% to 64,332 cars.
Asia-Pacific volume was down 17.1% to 198,849 vehicles.
China sales fell 20.3% to 138,960 cars.
First quarter deliveries in North America were 78,501 vehicles.
US sales were down 4.8% to 67,746 and Mercedes-Benz was the highest-selling premium brand there.