The Mercedes S400d 2021 S-Class pushes boundaries with game-changing technology and an even greater focus on refinement. The 400d offers petrol-like performance and almost 40mpg, while the upcoming 580e PHEV leaves rivals scrambling for a charging cable.

Every generation has pushed the boundaries of both luxury and technology – the S-Class was the first car to feature modern four-channel anti-lock brakes and adaptive cruise control – and the new one is no different, though you might have to look close to spot the slimmer headlights and retractable door handles that mark it out from the old car.

The S-Class all that effort went into making the cabin as library-like as possible. Even the diesel engine in our £94,135 S 400d was almost inaudible, except under hard acceleration. A turbocharged 2.9-litre six-cylinder, it’s more refined than some carmaker’s petrol engines, and goes better than some of them, too. With 325bhp and 700NM working through all four-wheels (a first for UK S-Classes) the S 400d 4Matic reaches 0-62mph in just 5.4 seconds, and yet Mercedes claims 38.7mpg.