What is it?
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.