FROM COMPETITION TO CONCOURS: POLISHING A DIAMOND Even a mere nutshell description of the Mercedes-Benz CLK GTR Roadster imparts just how special the model is: an open-top version of a homologation special whose competition iteration helped earn two consecutive Drivers’ and Constructors’ Championships for one of the most storied automakers on the planet.

Mercedes-Benz has left a more significant imprint on motorsports history than any other manufacturer, bar none—from the early successes of the pre-merger companies Daimler and Benz, to the record-setting interwar supercharged “Silver Arrows" of the state-sponsored factory team, to the postwar period’s dominating W196 Formula One and 300 SLR racecars, up through today’s seven-time F1 Constructors’ Champion Mercedes-AMG Petronas.

So it came as little surprise that after decades of relative abstention from factory-based competition, the Stuttgart-based automaker became a commanding winner in the German DTM series (Deutsche Tourenwagen M...