Mercedes' seven-speed automatic gearbox does a serviceable job around town but when pressing on, or when prompted via the wheel-mounted paddles for a quick change, it can pause for an uncomfortable duration while it decides what it wants to do next.
This, coupled with the engine's seeming lack of outright low-down torque, means rapid acceleration often requires a committed and lengthy application of throttle. Consequently overtakes may require a little more consideration than they would in something with a V8 or a dual-clutch transmission.
Enthusiasts may further be frustrated to find the Mercedes' stability systems to be overly intrusive. Accelerate sharply out of a junction, or happen to put one driven wheel onto a slick surface while accelerating, and – besides an annoying audible warning – the E 400's power is cut aggressively, resulting in an unpleasant jolt through the car.
While it's understandable that the manufacturer would prefer people kept on the straight and narrow, instead of pirouetting across the road, others manage to stabilise their cars without such pronounced and aggressive intrusion.
Hard acceleration also sees the Benz's economy tumble; our test car returned an indicated 20mpg during the road test and photoshoot, although it's likely that a figure nearer 30mpg should be attainable by most in everyday driving. A standard stop-start system, which operates promptly and without fuss, should help improve the Mercedes' fuel consumption for those who commute in heavy traffic regularly.
Through corners the E 400 proves suitably capable, with masses of front-end grip and good body control. There's plenty of traction on offer too and the substantial brakes bleed off speed with ease; the net result is a car in which it's easy to carry significant speed across country.
Only the steering lets the Mercedes down on the handling front. While accurate, allowing you to place the car on the road with ease, it frequently feels leaden and lacking in consistent weighting. At higher speeds, and with everything in 'Sport' mode, the AMG Sport Plus does feel considerably more composed and rewarding to drive, but suitable roads – and speed limits – are few and far between.
As you might expect, the Mercedes' more aggressive nature has predictably compromised its ride quality and refinement. Even with the dampers in 'Comfort' mode bumps and cracks in the road are transmitted into the cabin with a dull thud, and the Mercedes patters over broken surfaces. There's a notable amount of road noise on some surfaces too, although wind noise is pleasingly low.
While the exterior looks notably more modern than the previous generation, the interior still closely resembles that of the pre-facelift 2009 version and is distinctly lagging behind the likes of the new S-class. There's plenty of kit on offer but some of the finishing, for example the leather-trimmed dashboard that does little to conceal the integrated airbag, leaves much to be desired for such a costly car.