M 121. The same year, the Mercedes star atop the faux external radiator cap was made spring-loaded to give when bumped: reports at the time indicated that this was either to pander to the requirements of certain export markets, notably Switzerland, or to reduce the risk of pedestrian injury in the event of an accident. By 1959, the star was spring-retained on a ball base. A related roadster variant, the R121, better known as the 190SL, was produced from 1955 to 1963. At the 1959 Frankfurt Motor Show, in time for the 1960 US model year, a slightly wider grille and slimmer taillights were introduced. The same wider grille was carried forward to the car's (in other respects) more flamboyantly styled successors, when the Pontons were replaced by the W110 "Fintail" models during 1961. Technical description The Mercedes-Benz W 120 and W 121 are four-door saloons with a longitudinal front engine, and rear-wheel drive. Rolling chassis with either two or four doors were also available from the factory. The cars have a self-supporting body, the so-called "Ponton" body. The wheelbase measures 2650 mm, which is slightly less than the larger "Ponton" saloons' 2750 mm. In front, the W 120 and W 121 have independent double-wishbone suspension, in rear, they have either a double-joint swing axle (until September 1955), or a single-joint swing axle (from September 1955). Both front and rear wheels are coil-sprung; the front axle is fitted with a torsion-type anti-sway bar, and the rear wheels have additional hydraulic shock absorbers. Daimler-Benz installed a recirculating ball steering system and a hydraulic drum braking system in the 120- and 121-series. Mercedes-Benz built the W 120 with all of their then-present four-cylinder engines: the M 136 and M 121 Otto (spark ignition) engines, and the OM 636 and OM 621 Diesel (compression ignition) engines, with most W 120 and W 121 cars powered by either of the Diesel engines. The torque is sent from the engine to the rear wheels through a dry single-disc clutch and a synchronised, four-speed constant-mesh gearbox. The shift lever is a rather small lever mounted on the steering column. Models References External links the W120 Ponton presented by Mercedes-Benz Classic Center USA W120 W120 Rear-wheel-drive vehicles Sedans Roadsters 1960s cars Cars introduced in 1953 Limousines