For a long time the Diesel it was synonymous with a robust engine, but not very powerful and noisy. Suitable only for cars mainly used for work, without speed ambitions, but with the certainty of long duration, in terms of time and mileage. Cars like the Peugeot 504the Mercedes 240D and the Opel Recordwhich were designed to withstand hundreds of thousands of kilometers (and the goal of one million was not a utopia), with little need for maintenance and low costs: with powers between 60 and 80 HP, their engines included the presence of pre-heating glow plugs which required waiting a few moments before actually starting. Then, however, things slowly changed, thanks also to the arrival of the turbocharger, introduced first in competitions (especially by Porsche and Renault), then also on road cars, petrol and diesel. Thanks to this solution, the diesel was able to begin to offer higher performance, with powers in the order of 100 or more HP, contributing to the success of models such as the Mercedes 300 SD, the BMW 5 Series, the Volvo 740 TD and the Citroën CX Break, used in the station wagon version also for the rapid distribution of newspapers at the first light of dawn. Audi introduced direct diesel injection on the 100, which eliminated pre-combustion; Bosch created the common rail, developing a Fiat project, making the multiple high pressure injection system common which allows much higher performance. At that point, diesel had made a turning point: increasingly faster and more prestigious diesel cars began to whiz along the motorways (which, however, sometimes emitted clouds of black smoke when accelerating) and the Italian market share of models equipped with this type of engine, which until the early nineties did not reach 10% (also due to a surcharge), skyrocketed until it reached, between 2004 and 2006, values higher than 58%. At a certain stage, really everything with diesel engines appeared in the price lists, even coupés and cabriolets such as the Audi TT, the Alfa Romeo GT, the Mercedes Clk, the Peugeot 406, the Volkswagen Golf and the Ford Escort Cabrio, the Peugeot 307 and 308 Cabrio, the Opela Astra Twin Top and others. At that point, all that remained was to cover the very high performance car segment, which many manufacturers, especially German ones, rushed to do. And so the super-diesels with record power were born, which we want to remember here: coveted and desired engines, until the arrival, in 2015, of Dieselgate, the emissions scandal that was fatal for the fate of diesel engines, from that moment onwards towards a slow, but inexorable, decline.
