Ever wanted a BMW M4 with more? If the answer is yes, a Melbourne-based BMW dealership thinks it has the answer. And it wears an Alpina badge.

WHAT IS IT? German motorsport and tuning haus Alpina started life as a small company sticking flyers under the windows of BMW 2002s in railway station car parks, offering aftermarket turbocharger packages. It has since grown to become a carmaker in its own right; something of a BMW sub-brand that gives as much attention to the luxury side of the ledger as it does performance.

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MAIN RIVALS BMW M4; Mercedes-AMG C63 S Coupe; Lexus RC F

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PLUS: Exclusivity; individuality; stonking engine; exceptional ride and handling MINUS: Price; no manual option; would you really walk past an M4 to have one?

THE WHEELS REVIEW Sometimes a BMW adorned with the German luxury marque’s M badge isn’t enough. That’s where tuning haus Alpina steps in.

Alpina takes extraordinary BMWs and amps them up to extra-extraordinary. The two-door B4 Bi-Turbo, tested here, starts life as a BMW 4 Series but gains a heavily modified 3.0-litre in-line six-cylinder engine with an extra turbo plumbed in, suspension and chassis tweaks, and a more traditional torque converter automatic.

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Inside, the B4 feels plush. There’s patchworked, monogrammed and extremely supportive front sports seats, leather falls to hand at every touchpoint around the cabin, the steering wheel is finished in parallel-stitched – not cross-stitched like in ordinary BMWs – thread in contrasting Alpina red and blue colours, and the instrument cluster face and kick strips both proudly read “Alpina”.

In the middle of the centre console of our test car is a plaque reading “BMW Alpina B4 Bi-Turbo Coupe 041”, indicating the build number.

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On paper, the M4 will hustle from rest to 100km/h in 4.1sec; the B4 is only 0.1sec behind it. It’s the way the B4 delivers its power, though, that’s different. The M4 drives the rear wheels via a seven-speed DCT dual-clutch gearbox, but the B4 uses a ZF-sourced eight-speed automatic. Gear changes in the M4 are raw and visceral, banging through upshifts; in the B4 they seem almost as rapid-fire but slur almost imperceptibly.

Shifting the B4 into its more performance-focussed mode is a little more complicated than in BMW-badged equivalents. There’s still the console-mounted toggle switch for Sport and Sport+ modes, but they only alter the throttle, steering and stability control characteristics. You always need to flick the gearshift into “S” mode to get the auto to hold revs longer.

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Then there’s the ride. The B4 may sit on massive hoops ringed in a thin strip of Michelin 265/30 ZR20 rubber, which you’d think would ride horribly, but even on coarse, lumpy back roads the B4 soaks up perfections with aplomb. Even a section of our road test loop that has found the limit of the bump stops on many a sports car passed by almost unnoticed. The steering is crisp and well-weighted, and points precisely.

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SPECS Model: BMW Alpina B4 Bi-turbo Engine: 2979cc 6cyl, dohc, 24v, twin-turbo Max power: 301kW @ 5500-6250rpm Max torque: 600Nm @ 3000-4000rpm Transmission: 8-speed automatic Weight: 1690kg 0-100km/h: 4.2sec Fuel economy: 7.6L/100km Price: $160,900 On sale: Now