Mercedes-Benz S-Class, W 116 series (1972 to 1980) A brand-new premium-class vehicle generation was presented to the public in September 1972. The first officially designated “Mercedes-Benz S-Class” – internal designation W 116 – replaced the W 108/109 series and was initially comprised of three models: the 280 S, 280 SE and 350 SE. The 280 S and 280 SE models featured the six-cylinder engine M 110 with dual overhead camshafts that had made its debut in the W 114. Six months later the S-Class saloon was also offered with the larger 4.5-liter V8 engine in parallel to the 450 SL and 450 SLC. At the same time the 450 SEL was introduced, its wheelbase lengthened by an extra 100 millimetres; as with its predecessor models, the additional space served to increase legroom in the rear. The long version was also available from November 1973 as a 350 SEL and from April 1974 as a 280 SEL.
One noteworthy engineering innovation first featured as standard in the W 116 series saloons was the double-wishbone front suspension with zero-offset steering and anti-dive control, as tested originally in the C 111 experimental vehicle. This permitted further dynamic handling improvements. Rear suspension was essentially the same as the design that had by this stage been tried and tested over many years in the Stroke Eight models and which was also in use in the 350 SL. The 4.5-litre models were fitted with a coupled-link axle.
In terms of passive safety, too, the S-Class was at the forefront of engineering. The variety of safety design features integrated for the first time into the 350 SL were of course included without exception in the S-Class saloons. The fuel tank, for example, was no longer positioned in the rear end but above the rear axle for protection in case of accident; in the interior, maximum protection was offered by the heavily padded instrument panel, yielding or recessed switches and levers, and a four-spoke safety steering wheel with impact absorber and broad padded boss. The most significant improvement over the predecessor series was the even stronger safety passenger cell with stiffened roof-frame design, high-strength rigid roof and door pillars and reinforced doors. By controlling the deformability of front and rear end it was also possible to improve considerably energy absorption in the front and rear crumple zones.
Special wind deflectors on the A-pillars guaranteed good visibility. In wet conditions these served as channels for dirty water, keeping the side windows clean in bad weather. Other safety features included wrap-around turn indicator lamps that provided good visibility even from the sides, and large rear lights, which offered good resistance against soiling thanks to their ribbed surface profile.
The Mercedes-Benz 450 SEL 6.9
In May 1975 the company presented the 450 SEL 6.9 – the new top model in the series and true successor to the Mercedes-Benz 300 SEL 6.3. The powerful 6.9-liter V8 engine, developed from the highly successful 6.3-liter unit, achieved an output of 286 hp (210 kW) and maximum torque of 56 mkg (549 Newton metres). The hydropneumatic suspension with self-levelling – featured for the first time in a Mercedes-Benz passenger car – guaranteed the utmost in ride comfort. Other special equipment included in the standard specification for the top-of-the-range model were the central locking system, air-conditioning and a headlamp wash/wipe system. As was the case with its direct predecessor, the 450 SEL 6.9 proved an immediate success; although it was more than twice as expensive as the 350 SE, a total of 7,380 units were built during its four-and-a-half year production period.
Between November 1975 and February 1976 the direct fuel injection system in the 2.8-liter, 3.5-liter and 4.5-liter injection engines was converted to fall in line with more stringent emissions standards now in force in most European countries. The electronically controlled Bosch “D-Jetronic” was abandoned in favour of the newly developed mechanically controlled Bosch “K-Jetronic.” In all three cases conversion was achieved with only minor loss in output; at the same time, compression was slightly reduced in the 2.8-liter and 3.5-liter engines. For ease of maintenance these modifications also included breaker-less transistorized ignition and hydraulic valve clearance compensation for both V8 engines.
As with the 2.8-liter injection engine, compression was reduced also in the carburettor engine, similarly causing a slight decrease in output. Two years later, from April 1978, the original output was once again offered in all three models with injection engines. In contrast to the carburettor version, compression in the 2.8-liter injection unit was raised to its old value, and the previous output in the two V8 models was achieved largely by modifications to the exhaust system.