"Why do you think this was a merger or an acquisition?"
The reason I think it was a merger is, that it was a merger.
"The first Mercedes-Benz branded vehicles were produced in 1926, following the merger of Karl Benz and Gottlieb Daimler's companies into the Daimler-Benz company on 28 June of the same year."
Mercedes was a car name from the Daimlers side of the merger (from a car seller and racing team) - so it was Mercedes-Benz.
