From £73,8668

Diesel isn’t particularly sexy right now, but if anyone can instil it with an element of desirability, it’s Alpina.

And it really is all-round desirability that we’re talking about here, rather than excitement, because if the best known of all the BMW tuners (although it’s so much more than that) trades in any one attribute when it comes to crafting super-saloons, it’s extraordinary breadth, owing to the conciliation of apparent contradictions. 

So it is with this new D5 Sportdiesel, whose customary Alpina-logoed chin skirt and ducktail spoiler immediately present a persona at odds with the opulence of the interior.

There are other traces of duality. The seats are aggressively bolstered but prodigiously soft; a quartet of exhaust tips are a bit heavy metal for a sequentially turbocharged 3.0-litre diesel engine that never relinquishes its manners; and the leather-concealed Switch-Tronic gearshift buttons on the far side of the steering wheel suggest to you that this is a chassis only too happy to be pedaled, just not with a vigour that might elicit sweaty-palmed lunges for paddles the size of shoehorns.

Alpina has also tweaked the car's suspension geometry for greater negative camber on the front axle and fitted stiffer, shorter springs, yet the adaptive dampers include a Comfort Plus mode that's softer than that of the G30 BMW 5 Series donor car.

Consider also that the D5 S will nail 0-62mph in less than 5.0sec and yet still nudges 45mpg on the motorway, with little to impinge on the relaxation of you and your passengers beyond, perhaps, a touch too much tyre roar. Those 20in multi-spoke alloys are classic, mind.

How the D5 S stays true to Alpina's past form

The D5 S is fabulous inside, where the details are enough to keep you occupied for many minutes before you think about pushing the start button. Most notable is the digital instrument display from the 5 Series, which have been vividly re-skinned in Alpina colours and alter with each driving mode. There’s also the familiar plaque on the transmission tunnel, which now reads ‘Allrad’ – more on which in a moment.

With 322bhp, this massaged straight-six has usefully more about it than its 260bhp cousin in the range-topping BMW 530d xDrive M Sport. It’s an engine characterised by 516lb ft available from a lazy 1750rpm, which, as you can imagine, makes acceleration memorably short work, even for a car that tips the scales at nearly 1.9 tonnes.

It's peculiar, though, that those figures fall short of the 383bhp and 590lb ft D5 S owners outside the UK will enjoy. It makes the UK-spec car that rarest of things: a German performance saloon less explosive than its forebear. European models benefit from BMW’s tri-turbo diesel engine, which is an engine BMW never sold in a UK-spec 5 Series and, on the basis of this car, it wants to keep it that way.

Power levels have no impact on what has historically been one of Alpina's ace cards, though: ride. Again, in spite of those huge alloys, the D5 S glides down most roads in a barely interrupted flow. In fact, wheel travel is controlled with such conviction that it gives back to the driver some of the confidence lost through steering that's disappointingly – but almost inevitably – light on feel. 

The use of a less compelling engine, denied that third turbo, does however have implications beyond straight-line performance. This is the first diesel Alpina endowed with driveshafts front and rear, and for us, the dynamic blend between outright grip and adjustability sits fractionally too close to the former. An Alpina-specific dynamic traction control mode exaggerates the rear-biased torque split; it's decently satisfying if the road is damp, but it’s no panacea.

If point-to-point pace and security is your priority, this will bother you not a jot, of course, and progress is made all the more serene by an eight-speed ZF torque-converter automatic gearbox that’s quick-thinking and terrifically smooth. Body control is uncanny, too – closer to what you’d expect in a more focused 3 Series than any 5 Series barring, perhaps, the M5

How does the Alpina D5 S stack up against the competition?

If you like the D5 S, there's little to rival what it offers. The kicker is that the legendary residual value of Alpina cars is far from certain, given the nature of the powertrain.

Putting that to one side, the D5 S costs £62,000, to which you can add £1785 for adaptive dampers with electronically actuated stabilisers. For a further £995, there’s the option of four-wheel steering, which improves agility at speed and manoeuvrability when you’re pootling. The former expenditure is well worth it, the later less so.

From there, it’s possible to get very silly with options, and the car seen here – a cancelled order, intriguingly – costs a stomach-churning £86,690. The decal set is, naturally, a no-cost addition, but you pay for amenities such as a head-up display, heated seats, a powered tailgate and Apple CarPlay. With the stylistic flourishes that make an Alpina such a fascinating place to while away miles, you’d probably be looking at £70,000.

By comparison, the new Audi A7 Sportback with the 282bhp V6 diesel is priced from around £55,000, while the M5 now costs nigh-on £90,000. Perhaps those are not very helpful comparisons, but as an unusually powerful diesel cruiser with excellent etiquette and an abundance of character, the D5 S is in a class of one. As such, whether it’s worth the money will be a personal judgment.

Either way, each year around 1600 cars arrive at Alpina with a blue-and-white roundel on their nose and leave with carburettors and a crankshaft in its place. Most of these cars are diesel, and so this is an uncomfortable time for the 240 people on the Buchloe payroll.

In this instance, the machine they’ve delivered is nothing like as compelling as its petrol counterpartthe mighty B5 Biturbo – but remains a phenomenally broad-batted machine with no small appeal. It would be some injustice if it were sunk by prevailing attitudes. 

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