Start with what the Mercedes-Benz W03 is: a Torpedo bodied “Tourenwagen” / 4-door ”Pullman-Limousine” (sedan/saloon) / Various coachbuilt bodies supplied by independent coachbuilders with 1926–27: 2,968 , built from 1926 to 1930, the vintage years, when coachbuilders still shaped most of what was sold. What it meant takes a little longer.
The story
The Mercedes-Benz W03 was a large six-cylinder-engined automobile introduced as the Mercedes-Benz 12/55 PS and, initially, as the Mercedes-Benz Typ 300, by Daimler-Benz at the Berlin Motor Show in October 1926.
It was developed in some haste under the manufacturer's Technical Director, Ferdinand Porsche in parallel with the smaller Mercedes-Benz W 01 (which never progressed beyond the prototype stage) and the two-litre-engined Mercedes-Benz W02 following the creation of Daimler-Benz, formally in July 1926, from the fusion of the Daimler and Benz & Cie auto-businesses.
What is underneath
The engine is 1926–27: 2,968 other versions carried different engines, listed in the specification table below. The layout matters: a front engine drives the rear wheels, the classic proportion — long bonnet, cabin set back — that most people picture when they picture a sports saloon or a grand tourer. The wheelbase is 3430 mm. These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
Its place in the line
In the Mercedes-Benz line-up the Mercedes-Benz W03 has a clear place: it handed the line to the Mercedes-Benz W10; the factory was Stuttgart, Germany. The cars a buyer would have weighed it against include the Delage Type 15 S 8, the Bentley Speed Six, the Bugatti Type 41 Royale. Nearby in the Mercedes-Benz catalogue sit the Mercedes-Benz 300 SL and the Mercedes-Benz C124.
Owning one today
MotorJury scores cars on the United States complaint and recall record, and the Mercedes-Benz W03 has none: too old, too rare, or never sold there. Its value today is a collector's question, decided by provenance and condition rather than by a class average.