Large grand touring coupés from Mercedes built throughout the 1970s and 1980s were cars so dedicated to opulent ground-covering that few cars before or since have been able to equal them for refinement and comfort.

Car making has become a much more complicated and competitive business since then, of course, and tastes have changed sufficiently that even this E-Class Coupé comes with a downsized turbocharged V6, two driven axles and 19in wheels with low-profile run-flat tyres; all of which would have troubled the makers of Mercedes’ legendary W123 and W124-generation coupés, you suspect.

Nic Cackett

Nic Cackett

Road tester
Nine-speed gearbox has plenty of intermediate ratios for steep climbs

But although it would be nice to be able to exempt cars like this from the influence of modern emissions regulations and the need to produce competitive modern fuel economy, we can’t.

And thankfully, at least as far as the job that Mercedes has done on the E400’s engine is concerned, this car feels modern while still honouring the tradition of big-engined classic Benzes.

The twin-turbo V6 engine  is quiet, smooth, stout and rich. It idles almost noiselessly; produces greater low and mid-range torque than the atmospheric V8 this car might have had 10 years ago; and sounds sweet enough in its harder-working moments that you wouldn’t guess it was turbocharged.

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Neither would you really wish for something more mechanically exotic. The power and torque to accelerate this big two-door to 60mph in 5.6sec has to be deemed sufficient in something not primarily intended to go fast – and the readiness to do it with such silken reserve only confirms this engine’s fitness for purpose.

At a cruise, the shifts of the E400’s automatic gearbox are beautifully smooth and judiciously timed, and the fact that there are nine ratios in all makes the top one so long that the engine can spin well below 2000rpm at any sensible UK motorway speed.

Leave the Dynamic Select controller in Comfort mode and you can pick up speed effortlessly through early upshifts, leaning heavily on that turbocharged torque.

Select Sport instead and the gearbox will downshift and let the motor’s revs rise. The gearbox has a decent manual mode, but it doesn’t take long to realise that this is a powertrain configured for relaxed but swift progress – and it’s quite good at it.

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