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by Andrew Frankel 14 August 2014 Follow @@autocar Share
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As next moves go, this was not hard to predict. Hot on the heels of the spectacularly well received D3 Biturbo diesel saloon and estate, Alpina has now turned its attention to petrol-powered coupé and convertible versions of BMW’s 3 and 4 Series platform and this, the B4, is the result.
It costs almost exactly the same as an M4, produces almost as much power from a same capacity twin-turbo 3-litre BMW motor, and has a kerb weight within a couple of bags of sugar of an M4 (when also fitted with a paddle-shift transmission).
If you’re looking for a car that’s as fast as an M4, but easier to live with, then the B4 Biturbo would be an excellent choiceAndrew FrankelSenior contributing writer
It also has a 0-62mph within a tenth of a second of an M4’s, you’d be forgiven for wondering if the biggest difference between them is the letter that starts their names. But as with all things Alpina, the devil remains in the detail.
With its usual spectacular thoroughness, Alpina’s 50 development engineers (a statistically negligible number to any normal manufacturer) have taken a 440i donor car and gone through its engine, gearbox, cooling system, wheels, tyres, aerodynamics, steering and suspension.
For a company making just 1500 cars a year, this is an extraordinary commitment.
Power from the N55 motor rises from 315bhp to 404bhp, and while this is not quite so strong as the twin-turbo 431bhp S55 motor in the M4, its 442lb ft of torque is more than commensurately stronger than the 405lb ft offered by the M4.
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It’s kept the eight-speed ZF automatic transmission (disappointingly, and unlike the M4, no manual is available) but modified over 20 percent of its components for faster, cleaner shifts.
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On the chassis side, everything – springs, roll bars, dampers, bushes, bump stops – has been changed, but the overall strategy was to increase the springing medium by 40 percent while allowing more damping compliance in bumps and less in rebounds.
Alpina’s iconic 20-inch wheels, fitted with Michelin Pilot Sports developed specifically for the car, and vast Brembo brakes complete the picture. Note, however, that Alpina still does not provide a limited-slip differential as standard. It needs it less than a D3 but it still needs it and, at £1890, it is eye-wateringly expensive.
As for the B4’s standard equipment the coupé gets dual-zone climate control, adaptive suspension, cruise control, xenon headlights, 20in alloy wheels, a Dakota leather upholstery, electrically adjustable and heated front seats, rear parking sensors and BMW’s iDrive infotainment system complete with sat nav and DAB radio. Choose the convertible and the list will be similar to the coupé’s except for the folding metal roof.
Expect a savage road warrior, however, and you’re going to be very disappointed by the Alpina B4.
Despite its menacing quad-pipe Akrapovic exhaust system, the engine starts quite softly and turbine smooth. The ride seems a little fussy at first until you realise you’re hearing more than you’re feeling.
Despite liquorice proportions, those sidewalls are actually 20 percent softer than a standard Michelin of this size. If you leave the dampers in their default setting you can waft around all day in quiet and comfort. This has always been a key component of the Alpina proposition, and it’s here again, front and centre.
Nail the throttle, though, and you’ll find another side to its character altogether as in one silken wallop, it flings you up the road. The engine note is a smooth as a 1980s 2-litre six cylinder BMW, its thrust nibbling into junior supercar territory.