Towards the end of last year, we pitched the Alpina B3 Touring against the BMW M340d and Birds B3-40i for a 3 Series wagon face-off. All three were terrific in their own way (we've since welcomed the M340d onto the PH Fleet) but it didn't prevent the B3 towering above its more affordable rivals in the verdict. It was too fast, too luxurious and too ingratiating not to win. Too much like an Alpina, in other words: build a watertight case on paper, then bring it home in the real world in a way that apparently eludes most of the competition. BMW included.
Now it's the turn of the diesel-powered D3 S in the UK. Unlike the B3, which preceded the new M3 by half a year and therefore didn't have to suffer direct comparison with BMW's headliner, the D3 is very much based on the M340d - a model that's been building a solid case for itself over the past few months. It shares the same basic 3.0-litre mild-hybrid straight-six and associated AWD drivetrain, and does not promise prodigiously more from either. Outright power is up from 340hp to 355hp; peak torque climbs by 28lb ft.
There is not a vast disparity on asking price either. The M340d Touring currently starts at £52,045; the D3 S, £55,950. Obviously there is extensive ticking potential on both sides (our long-termer tops out at £62,615 and Alpina's test car is £70,760) but both cars come as standard with a generous amount of kit, including an electronically controlled limited-slip differential for the back axle and the all-important adaptive suspension.
Styling alterations aside, overhauling the chassis provides the D3 S with its most prominent point of difference. Most of the hardware changes spearheaded in the B3 are carried over, meaning you get the uprated Eibach springs and bump stops alongside new anti-roll bars. The damper rates have been revised too, and 1 degree of negative camber is introduced to the front axle. The same tailor-made ALP-designated Pirelli P-Zeroes feature on the 20-inch forged alloy wheels (assuming you've wisely opted to pay the £2,080 premium over the five-spoke 19s).
It is the accumulative effect of these changes that deliver immediately on the familiar Alpina promise. By any measure, the M340d provides its owner with a deftly managed compromise between the often conflicting demands of ride and handling - yet the D3 makes it seem like a job half done. Often it is a case of noticing what is not there: the minor palpitations that the BMW succumbs to when M-grade suspension and run-flat tyres meet poor surfacing at speed are almost entirely absent. The suppression of any abruptness from the car's initial spring travel is notable not just for the gains in refinement, but also for the superior sense of connectedness that comes with it.
While nonchalance in the face of pot-marked tarmac is clearly an advantage in the UK, it's the consistency of the response and its relationship with cannily controlled roll rates that mark the D3 out as a terrific steer. There's no float or flounder to the adaptive chassis in 'Comfort' mode when pressing on, just the impression that the car will let you lean into its sophisticated hold on the road with abandon. Even when lumbered with BMW's texture-light variable steering, there's precious little sense of aloofness or detachment. The D3 is the sort of car you savour driving at any speed.
In this respect, the reworked diesel lump is almost a better companion for Alpina's wagon than the 462hp straight-six strapped to the B3. Sure, it's a second slower to 62mph and not nearly as nice to listen to - but the tuner has always preached the advantages of heavy-duty torque, and 538lb ft from 1,750rpm is a relative superabundance even accounting for the Touring's 2,010kg kerbweight. The new peak is underwritten by a larger intercooler and improved cooling system, and while it isn't significantly quicker than the M340d, it seems subtly smoother and quicker to respond.
This is helpful because it's likely you'll drive the D3 subtly quicker than the BMW. Alpina has fettled the parameters for both the xDrive system and the rear diff, but the M340d already possessed a healthy preference for its back axle. The difference is driver mindset. Equipped with a surfeit of suppleness, poise and no little tenacity, it's hard to dial back an approach that seeks to exploit all three, all the time. The 'Sport' drive mode offers no relief either: resistance-heavy steering aside, it just makes the D3 hunker down that bit more, surge forward that bit more brusquely, and slash yet more minutes from predicted arrival times.
When you get to where you're going, you tend to look back longingly, too. The Alpina soaks up appreciative glances no less efficiently than it does bumps. The designers have not overindulged: there's the same gently reworked front and rear bumpers as appeared on the B3, with four chrome tailpipes exiting the latter. But it is enough to send the contentment gland into overdrive. Ditto the interior, which, if you ignore the contemptible dials, is a very pleasant place to be once you've factored in £1,900 worth of Merino leather trim.
Factoring in extra spend is really what the D3 is all about. It is a class act, no question. But one must really care about class to appreciate it. Fast wagons, especially oil-burning ones, tend to be likeable because there's something of the workhorse about them, and the cheaper M340d fills out that role more than adequately. It goes like stink, sips like a hummingbird, blends in like cornflour and accommodates no end of clutter. If you claimed to see no point in parting with more for a car that suggests it is no quicker on paper and yet walks the quoted economy back from 44.1mpg to 37.2mpg, it would be hard to mount a convincing argument.
But I'll try. The D3 S is the M340d as it would be in a perfect world. Alpina takes the premium and spends some of it on meaningfully better components. It reorders some of BMW's developmental priorities. It genuinely asks itself what a keen driver would appreciate day-to-day, and then sets about achieving it. The method has produced some outstanding road cars, and the latest D3 S is among them. As a means to an end the M340d is already an overachiever. But Alpina's version is something else. It is the best and most desirable diesel-powered car you can buy period.
SPECIFICATION | ALPINA D3 S
Engine: 2,993cc straight-six, turbocharged, diesel
Transmission: eight-speed automatic, all-wheel drive
Power (hp): 355@4,000-4,200rpm
Torque (lb ft): 538@1,750rpm-2,750
0-62mph: 4.8 seconds
Top speed: 168mph
Weight: 2,010kg (EU unladen)
MPG: 37.2 (combined, WLTP)
Price: £55,950 (starting; as tested: £70,760)
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