Top five reasons Alpina B5 beats BMW M5

Over the years Alpina has doggedly refused to limit the speed of its vehicles, but the latest B5 Biturbo is so fast it's finally had to make an exception.

Despite test drivers regularity reporting speeds exceeding 340km/h, its Pirelli tyres are officially rated to 'only' 330km/h so Alpina has had to, for the first time, add an electronic tether, reigning in the B5 to "around 330km/h".

Unless you own an airstrip, of course, being able to treble the national speed limit is completely irrelevant, until you meet a mate with an BMW M5 that can only clock a paltry 250km/h.

Despite using a similar powertrain as the M5, Alpina engineers have managed to squeeze 447kW/800Nm from its twin-turbocharged 4.4-litre petrol V8 - that's an additional 6kW and 50Nm over the BMW M-car.

In fact, the B5 Biturbo now produces so much torque that the standard ZF eight-speed automatic couldn't cope, forcing Alpina and the German transmission specialist back to the drawing board for a rethink.

Beefier internals, bespoke gears, a new transmission cooler and large torque converter allow the tranny to cope with the epic thrust that's on tap.

Order your B5 Biturbo from the factory and you'll be treated to a similarly bewildering choice of personalisation as a buyer of a high-end Rolls-Royce.

In fact, whisper it, some of the actual leathers available are the same as the luxury British car-maker's.

Once you choose them, a team of German craftsmen and women reupholsters your car by hand and adds the same level of attention to detail as rivals that cost 10 times as much. The result is a car that looks, and feels, like a million dollars.

You don't get that in your run-of-the-mill M5.

Alpina's minimalist design ethos means its aero additions for the B5 Biturbo, necessary to keep the super sedan stable at high speed, are more than subtle.

That's bad news for attention-seeking exhibitionists but great for someone more discerning who loves performance cars but likes to keep an ultra-low profile.

It means you can use it for work and shuttle the family around without anyone suspecting you're driving something with Ferrari-humbling performance on tap.

When you're not haunting supercar owner's dreams, the B5 does a better job of soaking up kays than BMW's M5 on a long road trip.

The standard Bilstein adaptive dampers offer Comfort and Comfort Plus modes that go even further in dealing with road imperfections.

Throw in a twin-turbo V8 that quietly settles down at a cruise and the large Alpina sedan is a wonderful place to soak up the miles and the rigours of everyday driving.

Active roll stabilisation, meanwhile, curbs body roll to such an extent that some passengers won't even realise when you pick up the pace.