Owner Daimler says the brand enjoyed a ninth straight year of record sales in 2019.
It shifted 2.34 million vehicles.
The Stuttgart-based firm says that makes it the biggest selling premium brand.
It's been helped by strong demand for SUVs and high-end limousines.
Sales in Germany, China and the U.S. all hit record levels.
It's a close battle with arch-rival BMW though.
Earlier in the week it too said sales had hit record levels - just over 2.5 million cars last year.
But a big chunk of that is accounted for by its lower-priced Mini brand.
Meanwhile, Volkswagen premium unit Audi sold 1.84 million, up 1.8% on the year.
While the rest of the auto sector struggles with falling sales, posh German cars seem to be doing just fine.
