mechanic, or navigator, depending on the race. As it turned out, this was only needed during the Mille Miglia, as the 1955 Carrera Panamericana was cancelled due to the 1955 Le Mans accident. On some circuits such as the Targa Florio the extra seat was covered and passenger windshield removed to improve aerodynamics. The front windshield for the two-seater mode was originally steeply raked, but due to intense turbulence in the cabin this was redesigned repeatedly during testing at Hockenheim before Mille Miglia. Jenkinson used the long curls of his trademark beard as flow visualization aids. Thus evaluated, the final design used at Mille Miglia ended up being near vertical. A total of nine W 196 S chassis were built: seven roadsters, and two coupés. Work was ongoing on an updated design for 1956 when Mercedes-Benz abruptly announced their withdrawal from all forms of motorsport following the Le Mans tragedy. The front suspension, the engine, and the brakes were being redesigned for this cancelled project; in parallel with the Uhlenhaut Coupés a coupé version had also been under development, with the aim of once again winning the Carrera Panamericana. Engine The M 196 S engine is a naturally aspirated straight-eight engine with a bore and stroke of , resulting in a displacement of . The engine has a peak power output of at 7400 rpm, with maximum sustained power of at 7000 rpm. Its maximum torque is at 5950 rpm, giving the engine a very high BMEP of . Like in the W 196 R, the engine was canted to the right at 53 degrees to lower the car's profile, resulting in slicker aerodynamics and a distinctive bulge on the passenger side of the hood shared with the streamlined Type Monza Formula one car. To reduce crankshaft torsion, power takeoff was from the centre of the engine via a gear rather than at the end of the crankshaft. Daimler-Benz fitted the engine with a single desmodromic intake valve, and a single desmodromic exhaust valve per cylinder, actuated by two spur-gear driven overhead camshafts. The fuel system is a direct fuel injection system with a mechanically driven eight-plunger inline injection pump made by Bosch. In addition to that, the W 196 S's engine was fitted with a dry-sump lubrication system and chromium-coated aluminium cylinder sleeves. For ignition, the engine was equipped with conventional double magnetos. Unlike the M 196 R engine,