Mercedes-Benz unveiled the W29 lineup in March 1934 at the International Motor and Motorcycle Show in Berlin.
The carmaker didn’t specify that it will replace the model 380 with the newly introduced 500, but the complete lineup with seven bodyworks available, apart from the bare-chassis version, raise suspicions. In June 1934, Mercedes-Benz introduced the new 500 on its price list, and in the following month, it retired the Typ 380. Two years later, the carmaker increased the engine displacement from five liters to 5.4 liters leading to a new designation name, the 540. The K came from the “Kompressor,” the German word for the supercharger. One of the rarest 540 K was the Cabriolet A. The carmaker offered the W29 with three open-top versions.

The Cabriolet A featured a pined-out radiator, pushed back from the bumper just behind the front axle. Its large front fenders supported the cross-beam with the big headlights and an additional set of fog lamps. On both sides, the carmaker placed the spare wheels between the rear-hinged doors and the front wheels. Mercedes-Benz built 116 units of them.

Inside, the carmaker insisted on exclusive materials. The fine leather and the wood veneers were perfectly combined with the polished metal from the steering wheel, and door handles. While other Cabriolet versions provided room for four, the Cabriolet A featured two seats at the front and a parcel at the back.

The chassis used was the long-wheelbase version, with front independent suspension and a rear swing axle with coil springs. Its 5.4-liter supercharged engine provided 180 hp when the supercharger was engaged. Mercedes-Benz paired the powerplant with a four-speed manual gearbox.