Khodrocar - If you’re in the market for a fast, luxurious coupé with more than 400bhp, you’ve likely considered the Mercedes-AMG C63, Audi RS5 and BMW M4. But for a touch of added exclusivity, you might want to consider an Alpina B4 S Biturbo.
The B4 S, which supersedes the old B4, is based on the same straight-six-powered platform as the M4, which has undergone extensive technical and aesthetic adjustments, as per Alpina’s traditions. It means the car is a more potent but less focused alternative to its BMW counterpart.
Under its svelte bonnet is a 3.0-litre six based on the N55 block of cooking 3 Series and 4 Series models, but it uses twin turbochargers that are 10% larger, a water-cooling system that’s 20% bigger and an uprated oil cooler with 35% more capacity. The engine spins a lighter crank that’s made from forged steel.
Maximum power output for the Alpina-fettled N55 peaks at 434bhp at 5500-6250rpm and torque reaches 487lb ft at 3000rpm. Those figures are 9bhp and 81lb ft more than the M4, although the B4 S, which only comes with an eight-speed automatic, is 90kg heavier than the auto BMW. Still, that added torque helps the Alpina to accelerate from zero to 62mph in 4.2sec, a tenth quicker than the M4.
Under the bonnet is where the technical improvements for the B4 S over the B4 end, though: Alpina has stuck with the same suspension settings, meaning it sits on slightly less aggressive springs and dampers than its cousin from BMW's M division.
As before, the B4 S gets BMW Professional infotainment as standard, which adds a widescreen sat-nav and all-round parking sensors. The car’s seats also come wrapped in Dakota leather at no extra cost, although the car you see here features Merino leather, a £1285 option.
Very approachable. From the press of the starter button to the first prod of the throttle in Sport mode, the B4 S is a docile beast. Where the M4 awakens with a deep-throated growl, the Alpina, blowing through its standard-fit Akrapovič exhaust, has a subtler, softer voice.
Leave the drivetrain set to its default Comfort mode and the only hint of its potential performance comes with the effortless way it shifts the car’s 1690kg mass. The engine barely treads over 2000rpm during normal urban driving and the gearbox flicks into seventh and eighth surprisingly often.
The benefit of the N55 lump’s Alpina modifications becomes clearest when it’s set to Sport mode and allowed to spin towards the redline. The engine is responsive from low down the rev band and there’s a very obvious kick at 3000rpm that’s accompanied by a silky in-line six-tone. On upshifts, there's a hefty shove in forward thrust.
Even with its more accelerative powertrain, the Alpina is better than the M4 in placing that power onto the tarmac. Where the M4’s grunt lands in one explosive strike that almost always seems to overcome the grip on offer, the Alpina’s more elastic motor transmits its power onto the ground with a rising surge. This means you can drive with more confidence than one does in the edgier M4 and it allows you to be more aggressive with the throttle on corner exits.
The M4, with its hunkered down body and significant weight advantage, turns and stops faster. But the Alpina’s less hard-edged suspension irons out creases and cracks in the road more effectively - impressive given that the car sits on big 20in Alpina Classic alloys. It makes maintaining a smooth pace along a B-road much easier and doesn’t require the wide-eyed focus of the M4 on a slippery surface.
Combine this with wonderfully consistent steering that feels perfectly weighted to a car with this much muscle, plus a highly responsive gearbox that can be controlled manually via Alpina’s shift buttons on the back of the wheel, and you have a car that is as flattering as it is rewarding to drive.
The beauty of the B4 S comes with the ability to then dial things back to Comfort and enable the car to waft along. The dampers loosen their grasp on the body and allow for a cushioned ride - a telling illustration of the effects of the B4 S’s more virtuous suspension set-up. It also emphasises the flexibility on offer from this less focused Bavarian coupé.
If there’s one thing to complain about from behind the wheel, it’s the comparative lack of high-tech infotainment on offer, which simply can't rival the Virtual Cockpit in the Audi RS5. But while the BMW system is lacking in theatre, in the Alpina its classically styled features and the fitment of traditional dials arguably suit the car’s more traditional luxury character.
While some of BMW’s M products are becoming increasingly garish, the Alpina represents a welcome return to the classic, subtle performance car formula.
Someone after the sharpest, hardest hot coupé will be best looking at the batch of aforementioned rivals, but enthusiasts who desire a slick-looking coupé that is as relaxing as it is rewarding to drive need look no further.
It’s fast, comfortable and stylish, and so rare that you’d be hard-pressed to see another on the road in Britain. For a sports coupé in this price bracket, that’s a highly compelling recipe.