Mercedes-Benz has spent the past quarter of a century trying to build an executive saloon to match the sportiness of rivals from BMW. Now, though, with its new E-class, it has given up the chase and returned to what it does best — building cars of unparalleled quality. And guess what? This new E-class is a winner.

Although it’s a high-tech product, at its heart lie some traditional but seemingly lost Mercedes values of yore. There was a time when Mercedes cars earned the manufacturer a reputation for unrivalled mass-production quality, though this has become tainted of late with the pursuit of cost-cutting apparently taking priority over product quality, new cars seeming to favour style over substance.

Ironically, though, it may yet be the case that the new E-class beats the BMW 5-series anyway, as for once it has caught its nemesis in the autumn of its life. Better still for Mercedes, the rival Audi A6 is a disappointing car, while the Lexus GS is an intriguing but flawed niche player. And as for the Jaguar XF, with its sloping roof and sleek proportions, that’s more akin to the Mercedes CLS Coupé than the upright E-class saloon. In short, Mercedes may well have ended up with the class-leading saloon it always craved.

There is, however, a minor hurdle to leap over, and that’s the car’s looks. While its overall proportions are classic Mercedes saloon, the detailing — particularly around the front lights — contrives to make the newcomer look as if it’s pulling a face.

The cabin — a case of evolution rather than revolution — fares better, providing a bit more space in the back, offering a touch more style in the front, and representing a considerable forward step in terms of the ease and clarity with which it relays information to the driver.

The E-class has defied the apparently immutable law that says every new car in this class should be more sporting than the one preceding it. Talk to Mercedes designers and engineers, and they’ll discuss its quality, comfort, refinement, ergonomics, space and efficiency long before they talk about its sportiness. It just wasn’t high on their agenda.

You sense this the moment you set off, in my case in an E 250 CDI — diesels will account for some 85% of sales when the E-class reaches UK dealer showrooms in June. With a 204bhp, four-cylinder engine that uses less fuel and emits less CO2 than a 60bhp 1.2-litre Skoda Fabia, the E 250 CDI is likely to be the pick of the bunch. It glides along the road on supple springing, and steers slowly but with pinpoint accuracy into the bends. Its every action is smooth, fluid and considered, and in this way it strikes a stark but not unwelcome contrast with the urgent responses of its classmates.

On paper, the new engine seems unbeatable, offering more power and torque, yet significantly lower emissions and fuel consumption than its rivals. While nobody would quibble with what it does, the way it does it is not entirely satisfactory. There is a distant but unmistakable clattering sound that is incongruous to the refined air of the robust cabin. All four-cylinder diesels make this noise, it’s just that some are better at keeping it to themselves.

A brief drive in two petrol-powered versions, the E 350 CGI and E 500, revealed them to be much more softly spoken (and the latter ferociously quick). Regrettably, in Britain, their high running costs relegate them to playing bit parts within the range.

Noisy diesels aside, the new E-class proves that a car need not have a sporting character in order to deliver a satisfying driving experience. It won’t scream around corners in the manner of a Porsche, nor quicken the pulse as does a Lotus . . . but then, nor will any rival.

What the E-class does is expose the compromises in comfort accepted by others in their attempts to confer sportiness upon saloons whose very size and weight conspire against this aim. By contrast, Mercedes’ decision to apply modern engineering technology to an old way of thinking shows that a car can be supremely comfortable and have the feel of a precision instrument. In short, soft need not mean sloppy.

The soothing manner and low running costs of the new E-class will count for much, as will the driving pleasure it provides. Indeed, were it a touch better looking, and that diesel engine a little quieter, I think we’d be looking at a landmark in executive car design. As it is, though, it will have to settle for just being the best in its class.