Alpina’s tweaked BMW understated with sporting intent

We find out whether the super-fast Alpina B4 Biturbo really is a quality alternative to the BMW M4 Convertible


Alpina has a long-standing reputation for taking all the key cars from BMW’s line-up and tweaking them in special ways.

With the B4 Biturbo, the German tuning company has brought in a BMW 435i convertible, taken away the standard car’s single turbocharger and replaced it with two instead. That results in a car which produces an amount of power within striking distance of a BMW M4 Cabrio but with more torque too.

Of course, the car also gets Alpina’s styling tweaks. There’s the standard 20-inch multi spoke alloy wheels and aerodynamic kit. There’s also a rather nice four-pipe Akropovic exhaust system at the back, to let you know that this isn’t any old BMW convertible.


Alpinas have always been able to manage the look of a car that is understated, but shows sporting intent too. The B4 Biturbo convertible continues this.

There’s the previously mentioned bodykit, which includes a front splitter. You’ll also find Alpina pin striping along the flanks of the car. This may not be to everyone’s taste, but in our eyes, it looks fantastic. The large multi-spoke wheels finish the exterior look, and a ducktail spoiler at the rear looks the part too.

Inside, it’ll be familiar to anyone who has seen or driven a current-generation 3 Series. BMW’s excellent infotainment system remains, controlled by the i-drive rotary selector in the centre of the car.

There are, of course, certain elements of the interior that have been tweaked by Alpina. The steering wheel, for instance, is thin and trimmed in alcantara, rather than the much thicker BMW M-Sport one. There’s a leather-trimmed dash too, though on our test car, this was a hefty option. Blue and green stitching is used throughout the cabin, while a numbered metal plaque makes you fully aware — if you weren’t already — that you’re driving something a little bit special.


Despite having seating for four, the B4 Convertible — much like the BMW car on which it is based — can never claim to be a fully-fledged four-seater, rather a 2+2. The rear seats would be fine for children, but for longer trips, adults are going to find it a bit of a squeeze.

Up front, however, there’s plenty of room. Legroom is decent enough, while there’s plenty of space for bottles and all manner of other items. Two large cup holders are useful too, especially on hot days with the roof down. However, that roof does affect practicality somewhat.

If you’d like to fold it away, you have to first lower the luggage cover in the boot, heavily compromising the area’s space. It’s a small thing, but users looking to have the roof lowered frequently may find it annoying.


Make no question about it, the B4 Biturbo is a quick car. Putting out 410bhp and 600Nm torque, it’s able to reach 62mph in 4.5 seconds and won’t stop until it reaches 187mph.

However, the car’s approach to those figures isn’t as aggressive as you might think. Powered through an eight-speed ZF automatic — as opposed to the M4’s twin-clutch unit — the Alpina wafts up to speed in a much more relaxing fashion than the bodykit would allow you to imagine. That exhaust, despite looking more boy racer than B-road bruiser, isn’t intrusive in the slightest, only giving away a lovely, mechanical note under heavy acceleration.

Alpina makes sure to thoroughly change the suspension on any car it makes, and the B4 is no different. The wheels, though wearing 245/30 section tyres, bear no impact on the car’s ride.

In fact, you’d be hard-pressed to find a car that deals better with bumps in the road than this one. It manages to be firm without jarring, which is just what you want in a convertible.

This is bettered even further by placing the car in comfort mode. Up and running, the B4 Biturbo is easy to drive quickly, with the vast amount of torque on offer making any change of pace quick and effortless. It also means the car is relaxing to drive on the motorway too.

The B4’s steering is also excellent, helped no doubt by the thin-rimmed wheel. Alpina still curiously chooses to use buttons mounted behind the wheel rather than paddle shifters, which is one thing we’d change.

That ZF gearbox still provides excellent shifts time after time, though. One annoyance was the start-stop system, which had a habit of cutting in incredibly early, and then starting again with a jolt.


The B4 Biturbo starts at £62,950 (no prices available for Ireland). Our test car, fitted with options such as adaptive headlights and Merino leather, came in at a hefty £72,010. Make no mistake, this Alpina is not a cheap car. For that though, you get a level of subtleness that is hard to describe.

Those who know of Alpinas will appreciate the car, while those who are unaware may see it as a 3 Series with a large bodykit and a set of wheels — but that’s what Alpina cars are about.

Given the performance available, the car’s price makes sense. When you also take into account the bespoke nature of the car’s suspension and powertrain, as well as the interior, then it begins to look like good value. Its price is perilously close to its BMW rivals though, which is another consideration.


If you’re looking to stand out from the crowd, the Alpina perhaps isn’t the best choice. If, however, you fancy driving a car that has understated presence hiding a vast amount of performance, the B4 Biturbo may well be for you.


Model: Alpina B4 Biturbo (€74,130 base. No prices for Ireland).

Engine: 3.0-litre twin- turbocharged straight-six.

Transmission: Eight-speed ZF.

Performance: 0-62mph in 4.5 seconds, top speed 187mph.

Economy: 35.3mpg (combined).

Emissions: 186g/km CO2.


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