BACK in late 1979, when Mercedes-Benz unveiled the W126 S-class at the Frankfurt motor show, it represented everything the almost century-old maker knew about cars. Its engineering depth ensured that it reigned supreme throughout the 1980s, seeing off two generations of BMW 7 Series, the all-new Jaguar XJ40 and Audi's flawed V8. So much so, in fact, that it was the yardstick for Toyota when it developed the first Lexus, the LS400, in 1989 - and that was a decade after the S-class debut. The W126's follow-up was the gargantuan but awesomely capable W140, a car so out-of-step with the lean and mean recessional early-1990s that Mercedes rather too hastily abandoned its hallowed "over-engineering" policy for something a lot more pedestrian: making as much money as it could. A decade on from that and the company is a very different entity to that it once was, with a brand that's been stretched woefully downmarket, undoing a previous century's hard work. Meanwhile its W126 models, featured here in 1986-1992 300SE guise, stands as a timeless example of what the old, much-lamented Mercedes-Benz used to be about...