Mercedes’ particular mechanical specification for the E400 puts the car on low-profile run-flat tyres and air suspension as standard (whereas its less powerful range mates can be had with steel coil springs if you prefer).
This is something of a regrettable combination because run-flats tend to introduce a little bit of harshness into any car’s ride compromise on account of their necessarily stiff sidewalls – and since air suspension is ill-suited to the dampening of that harshness, the chassis’s solution to the typical UK B-road dilemma can seem ungainly.
Curiously, it is in Comfort mode where the mis-match tends to irk most. The coupé’s softest setting is well-meaning enough and its syrupy pitch and heave are obviously intended to keep you at an E-Class-sized distance from the road surface. But it only works on motorways and the smoothest of A-roads.
Away from them, rather too obviously and often, the experience of the suppleness is thwarted by obstacles too tall, deep or sharp for the suspension to mitigate before gracelessly registering with the occupants above.
Better instead to drive in Sport mode, where the impression of a fast modern pseudo-performance coupé becomes far more consistent. True enough, the bristling response to B-road abnormalities remains, except now it occurs against the background of a much more closely damped attitude to body control. As well as making the coupé more purposeful, the difference causes a generous resetting of driver attitude, making the secondary infractions forgivable in the light of a sportier bent.