Buchloe, Germany - This, says Alpina tuning haus CEO Andreas Bovensiepen, is the world’s fastest production station wagon, the Alpina B5 Bi-Turbo Touring. And, with a top speed of more than 325km/h, he’s unlikely to find many challengers for the title.

It is, of course, based on the latest (G30) BMW 5-Series Touring, powered by a seriously tweaked (447kW!) version of BMW’s N63TU2 4.4 litre V8, with uprated piston and spark plugs, a new big-bore, two-stage intake system that has a main intercooler feeding two large-volume, close-coupled intercoolers for shorter intake paths, two specially-developed, twin-scroll turbochargers delivering up to 1.4 bar of boost, and bigger inlet and outlet ports for improved throttle response and a wide, flat torque curve.

Bovensiepen quotes 670Nm at just 2000rpm, with peak torque of 800Nm from 3000-5000rpm, while two additional water radiators and one additional oil cooler keep engine temperatures under control.

The four-tailpipe stainless-steel sports exhaust system has been tuned to reduce back pressure and deliver a choice of two driver-selectable, bass-focussed soundtracks.

The as-issued ZF eight-speed automatic transmission also gets an additional oil cooler, along with strengthened gear clusters and a bigger torque converter. The Alpina-modified cogset is so much tougher than the standard kit that the torque reduction applied by BMW’s factory software during upshifts isn’t necessary, helping the B5 to hit 100km/h in just 3.5 seconds off a standing start.

The donor car, of course, comes with BMW’s active rear steering, roll stabilisation and all-wheel xDrive; the latter’s software is re-written in Buchloe to feed up to 90 percent of the torque the rear wheels. A mechanical limited slip differential is available as an option.

Shorter, stiffer front springs, bespoke Alpina rear air suspension and custom-tuned adaptive dampers lower the centre of gravity, and offer an additional Comfort Plus mode for a really plush ride. Special front suspension wishbones with one degree of negative camber and re-written software for the electric steering improve turn-in and steering feel, as do bespoke lightweight 20 inch forged-alloy rims shod with specially-developed ‘ALP’ labelled Pirelli P-Zero tyres.

Unusually, the rear disc brakes are larger than the front (because they receive less cooling air, so need a larger surface area to shed heat, says Bovensiepen). This setup, he says, delivers more stopping power and better resistance to fade than many equivalent ceramic systems.

A special Alpina front splitter and rear spoiler (developed in BMW’s wind tunnel) help to increase airflow through the uprated cooling system.

Hand-crafted interiors

Standard kit on the new B5 Bi-Turbo includes soft nappa leather trim, ceramic-finish control surfaces, Alpina roundels on the seat backs, a hand-finished sports steering wheel in Lavalina leather with blue and green contrast top-stitching - and of course, a numbered plaque on the centre console.

You can, however, ask for any interior finish you want, in an almost limitless range of colours and wood-veneer trims.

Pricing for the Alpina B5 Bi-Turbo Touring starts at €96 891 (R1.43 million) ex factory, and this is what you get:

IOL Motoring