Mercedes-Benz began at a very early stage to investigate the use of alternative drive systems in the 123 model series. In 1983, for example, a 280 TE was fitted with a hydrogen drive system, following in the wake of a 1982 experimental vehicle with electric drive system, also based on the Estate model. And as far back as 1981 Mercedes-Benz had presented a 200 model with a bi-fuel drive system (liquefied petroleum gas and petrol). There was thus already an indication of the importance that alternative drive systems would take on for future generations of the Mercedes-Benz intermediate model series, even four decades ago. The 123-series Saloon was built until November 1985; the era of the no less successful 124 series had begun ten months earlier. Production of the especially successful Estate models in the 123 series even went on until January 1986. From 1975 until 1986 almost 2.7 million vehicles were manufactured, the highest proportion of these being Saloons with normal-length wheelbase (2,375,440 units). 199,517 units of the Estate were built, along with 99,884 Coupé vehicles. In addition to these there were 13,700 long-wheelbase Saloons and 8,373 chassis as a basis for special bodies. These days the 123 model series has long been recognised as a classic – and remains as fascinating as it was at its launch 40 years ago.