Scroll through the performance control menu to Sport and the chassis tightens its grip on the road while throttle response sharpens. The suspension becomes noticeably firmer, losing the occasional floaty feeling you get in Comfort at speed, without ever becoming uncomfortable. There’s a bit more heft to the steering, too.
As you start to travel faster, you notice the alert front end sending subtle messages through the wheel rim. When your confidence increases, the amount you push the throttle will no doubt increase. Doing this - especially with the gearbox also in Sport mode – completes the transformation from comfortable family wagon to performance monster.
The previously docile engine is suddenly delivering its huge reserves of torque to the rear wheels more urgently, making the optional limited-slip differential seem like a very good idea, even at a stiff £1900. Assuming the rear tyres hook up, you're launched towards the horizon at a pace that would previously have been the preserve of much more exotic machinery.
Of course, there’s no guarantee you’ll find the necessary traction, especially on greasy roads. It doesn’t take much throttle to get the rear end edging round, although it is easily gathered up. While xDrive is available on left-hand drive models, it's not an option on UK cars due to packaging constraints.
While the engine may not have the kind of top end reach and thirst for revs many performance enthusiasts crave, riding the wall of torque between 1500rpm and 3000rpm is addictive. The industrial-edged six-cylinder roar coming from the quad pipes certainly helps, too.
Should I buy one?
If you have the cash then yes, undoubtedly yes. The only issue is that having the money could be a problem for much of the UK’s population. Alpina itself suggests it's the choice for automotive gourmets, and the pricing of its products reflects that.
At £49,950, it’s already around £8000 more than BMW’s own 335d xDrive. When you add niceties such as extended leather packs, a panoramic roof, limited-slip diff and upgraded infotainment, our test car came in at more than £65,000.
An M3 is faster but won’t be anywhere near as exclusive. Alpina will make fewer than 2000 cars this year, split over several model lines. The extra attention it can pay to each and every car really shows in everything the D3 does. If I could pick only one car for every occasion, this would be it.
Alpina D3 Biturbo Touring
Location Storrington, West Sussex; On sale Now; Price £49,950; Engine 6 cyls inline, 2993cc, twin-turbocharged, diesel; Power 345bhp at 4000rpm; Torque 516Ib ft at 1500-3000rpm; Kerb weight 1730kg; Gearbox 8-spd automatic; 0-62mph 4.6s; Top speed 170mph; Economy 52.3mpg (combined); CO2/tax band 142g/km, 26%