hardtop roof, designated as 230 SL. The 230 SL made its debut at the Geneva Motor Show in March 1963, where Nallinger introduced it as follows: "It was our aim to create a very safe and fast sports car with high performance, which despite its sports characteristics, provides a very high degree of traveling comfort". Designed-in safety The W 113 was the first sports car with a "safety body," based on Bela Barényi's extensive work on vehicle safety: It had a rigid passenger cell and designated crumple zones with impact-absorbing front and rear sections built into the vehicle structure. The interior was "rounded," with all hard corners and edges removed, as in the W 111 sedan. The W 113 was also the first Mercedes-Benz with radial tires. Models 230 SL (1963-1967) Production of the 230 SL commenced in June 1963 and ended on 5 January 1967. Its chassis was based on the W 111 sedan platform, with a reduced wheelbase by , recirculating ball steering (with optional power steering), double wishbone front suspension and an independent single-joint, low-pivot swing rear-axle with transverse compensator spring. The dual-circuit brake system had front disc brakes and power-assisted rear drum brakes. The 230 SL was offered with a 4-speed manual transmission, or an optional, very responsive fluid coupled (no torque converter) 4-speed automatic transmission, which was popular for US models. From May 1966, the ZF S5-20 5-speed manual transmission was available as an additional option, which was particularly popular in Italy. Of the 19,831 230 SLs produced, less than a quarter were sold in the US. The M127.II inline-six engine with and torque was based on Mercedes-Benz' venerable M180 inline-six with four main bearings and mechanical Bosch multi-port fuel injection. Mercedes-Benz made a number of modifications to boost its power, including increasing displacement from , and using a completely new cylinder head with a higher compression ratio (9.3 vs. 8.7), enlarged valves and a modified camshaft. A fuel injection pump with six plungers instead of two was fitted, which allowed placing the nozzles in the cylinder head and "shooting" the fuel through the intake manifold and open valves directly into the combustion chambers. An optional oil-water heat exchanger was also available. Mercedes-Benz Chief Engineer Rudolf Uhlenhaut demonstrated the capabilities of the 230 SL on the tight three-quarter mile Annemasse Vétraz-Monthoux race track in 1963, where he put up a best lap time of 47.5