The initial model line-up consisted of a 250S, 250SE and 300SE, as well as a single W109 series, 115mm longer wheelbase 300SEL, which heralded all future S-Class models having an LWB derivative. In November 1967, the three W108 models were replaced with the 280S and 280SE and were known as the ‘stroke 8’ models – identified on the body plate as ‘/8’. Both were powered by the M130 2778cc six-cylinder single overhead-cam engine. However, the 280S was fuelled by two twin-barrel Zenith carburettors, and with a 9.0:1 compression ratio developed 103kW at 4200rpm and 223Nm of torque at 3600, whereas the SE boasted Bosch mechanical fuel injection. Running a 9.5:1 compression ratio, the injected motor, which incorporated temperature and altitude compensation, produced 118kW at 5500rpm and 240Nm at 4250. Molybdenum-coated piston rings were used for extra reliability and longer service.
The standard transmission for Europe was a four-speed manual with the option of a four-speed automatic that was developed and built in-house – unusual for a mainstream European manufacturer of the time. Taking into account such factors as weight and gearing, the power and torque differences gave the 280S a top speed of 185km/h and the 280SE 193km/h, but for both models the 0-100km/h time was around 10.5 seconds. Claimed overall fuel economy was given as 10.5 litres/100km.