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Niche manufacturer Alpina serves up its take on a fast, six-pot 3 Series

The Alpina B3 isn’t an M-car. Yes, it’s a powerful BMW 3 Series, yes, it’s exclusive, yes, it’s fast and yes, it’s on the reassuringly expensive side. But if you know Alpina, you’ll know it does things differently.

Within the automotive world, the relationship between Alpina and BMW is a rare and precious one. BMW, global player though it is, doesn’t just tolerate the independent company Alpina – registered as a manufacturer in its own right 30 years ago – but genuinely enjoys its relationship with it, to the extent that a high-performance Alpina will usually arrive long before an M division version of the same model.

Prefer traditional Alpina blue or green paint? We like ‘em both, but they’re a pricey option.

This time, the engine modifications run quite deep; BMW didn’t offer such a twin-turbocharged six at the time, but now offer it in the shape of the 340i. It takes the number of Alpina models currently on sale to an impressive seven, adding up to a total volume of around 2000 units a year, and they can be serviced at any BMW dealer.

Such is the case here with the B3 Biturbo, a 404bhp variant of the latest F30/F31 3 Series in the finest Alpina form: with a twin-turbo straight six engine, automatic gearbox and subtle modifications to chassis and design.

Alpina has been fettling the BMW 3 Series for almost as long as there has been one to fettle. The earliest cars, based on the original E21 and badged A1/3, were delivered to Buchloe for tuning post-build.

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By 1978, the firm was introducing models developed and partially built in-house, including the legendary six-cylinder B6 2.8 — a car that actually pre-dated BMW’s own M20-powered 3 Series. By 2007, and the introduction of the 3.0-litre B3 Biturbo, Alpina had sold nearly 6000 examples of its successors.

Alpina's unusual relationship with BMW generally produces some intriguing and, by and large, thoroughly alluring products.

Let’s see if it’s the same this time.

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DESIGN & STYLING

Classic 20in alloys on Alpina B3

To a large extent, visually at least, you know what you’re going to get with an Alpina: multi-spoke alloy wheels with threateningly low-profile rubber and subtle, often angular body additions.

A couple of our testers thought the styling a touch fussy around the front of the latest 3 Series and others – the majority – that it was right in keeping with Alpina’s heritage. Either way, those who know about Alpina will know this is an Alpina. Ditto with those 20-inch alloys, which are covered in, perhaps crucially, rubber that isn’t of the runflat variety.

Alpina doesn't tamper with BMW's classic formula, so the longways straight six is still up front, driving the rear wheels

The tyres are the most outwardly apparent elements of a thorough overhaul of the 3 Series’ dynamic make-up. The suspension is, of course, based on the latest F30-series 340i with adaptive dampers, but the B3 wears bespoke Eibach springs that are 45 percent stiffer and has its own bump stops and Alpina-specific anti-roll bars (albeit sourced from BMW).

There is more negative camber, while the front subframe, with a strut brace, has been redesigned, partly to increase body rigidity and partly by necessity, because the B3 gets a twin-turbocharged, rather than single-turbo, variant of BMW’s 335i engine that headed the range at launch.

Alpina says this is because its two smaller turbochargers take less time to spool than even BMW’s twin-scroll turbo. A twin-scroll inlet for a single turbocharger negates some of the lag associated with a large turbo, which is why BMW adopted it for its N55 six-cylinder engine. With such a turbocharger, incoming exhaust gases are separated into two scrolls (the curved pipes that circumnavigate the turbo housing and direct exhaust gases towards the turbine).

On a straight six, each scroll takes its gas from three cylinders – those whose exhaust valve cycles don’t overlap – which in turn makes for more efficient spinning of the turbocharger. Typically, the scrolls pump gas at the turbine at different angles and pressures from each other (and even on to different parts of the turbine) — one scroll to provide quick response, the other for peak performance.

However, Alpina believes that two smaller turbochargers are quicker still to respond, hence it has junked the N55’s single, twin-scroll turbo and developed its own twin-turbo solution. This requires use of twin-turbo-capable flanges, which are already cast into the N55’s aluminium crankcase – handily leaving the door open for the return of two turbos on the upcoming BMW M3 and M4.

Alpina's tweaked engine also has a forged steel crankshaft, Alpina-specific ECU and wiring loom, NGK spark plugs, a high-performance fuel pump and a 40 percent bigger intercooler than that used on the BMW 335i.

The upshot of all these modifications is that the 3.0-litre straight six, which drives the rear wheels through a ZF eight-speed automatic transmission, produces 404bhp and 443lb ft – a particularly impressive result, especially when you consider that the claimed combined fuel economy is 37.2mpg.

Other notables include Alpina’s own tuning of BMW’s variable sport steering (which quickens off the straight-ahead; it’s not active steer) and stability programs, and an optional (but not fitted here) limited-slip diff. Brake discs are ventilated, not drilled, and 370mm in diameter at the front, 345mm at the rear.

The B3 Biturbo is also available in the more practical outfit of the 3 Series Touring, which gives a compelling mix of power and practicality in one dosage.

INTERIOR

Alpina B3 Biturbo's interior

There’s little that’s particularly special about the Alpina B3’s cabin, or that lifts it very far above the baseline level of a well equipped 3 Series in terms of richness or style. That, however, isn’t a big criticism, given how much there is to like about the current 3 Series cockpit anyway. There’s space, solid material quality and the usual smart BMW business-suit ambience to enjoy.

The front sports seats offer excellent support and comfort, of the sort that makes miles on the motorway simply melt away. But there isn’t a great deal of added performance flavour of the kind you’d expect in a Mercedes-AMG or an Audi RS.

The Alpina B3 comes with an admirable amount of kit as standard

Alpina gives you adaptive suspension, dual-zone climate control, DAB radio, a quad-exhaust Akrapovic exhaust system, LED headlights, rear parking sensors, heated front sports seats, leather upholstery, and BMW's iDrive infotainment system complete with sat nav, Bluetooth and USB connectivity as standard.

It may seem slightly tight-fisted, but the company’s strategy is not to inflate list prices with what some would consider extraneous technology, knowing that you can add things such as the Harman Kardon sound system, an in-car TV or a head-up display if you want to.

And, for the most part, it’s a philosophy of which we approve, provided it keeps the basic price of the car low enough to make it look attractive next to an M division equivalent.

You can, after all, choose from five different leather colours and four different cabin veneers in this car, and then from various stitching and finisher themes on the top.

ENGINES & PERFORMANCE

Alpina B3's twin turbocharged engine

Accessible torque is something the BMW Alpina has long since traded on, and it has always made for a fairly stark contrast with M division’s official go-faster saloons, which were fitted with high-revving atmospheric engines – until recently, at least.

Alpina’s twin-turbo solution makes this car smooth and responsive at low revs, when the smaller compressor is providing the boost. There is very little softness in the accelerator pedal – just precision and proportionality. Which is to be expected from a company that knows the value of driveability in a road car.

The Mercedes-Benz C63 AMG's 6.2-litre V8 is memorable in a way the Alpina could never be

So when you ask for 40 percent of engine performance, that’s exactly what you get, and you get it pretty smartly – unlike some high-output turbo engines, where it’s as if you have to ask for 60 percent before feathering the accelerator to get the desired 40 percent.

The true pace of the B3 is better reflected by in-gear acceleration than the standing-start numbers we recorded. The 30-70mph dash can take as little as 4.2sec in third gear, a still-muscular 5.3sec in fourth and 7.3sec in fifth.

This is instant, generous, real-world speed of the ‘no sooner said than done’ variety. If you put the gearbox in manual mode, the B3 feels brisk largely irrespective of gear, across a broad speed range. But left in ‘D’, the accelerative experience is even more convincing. The ZF eight-speed auto brilliantly makes the most of that pulling power, upshifting as and when you’d want it to and only kicking down when you expect.

The price to be paid makes itself known the instant the bigger of the two turbos comes on boost and peak torque is delivered. At full throttle, this happens in a slightly unceremonious rush that’s in conflict with the smoothness of the engine’s delivery everywhere else.

You could say it adds drama, and on the track it’s possible to drive around the problem most of the time. But not always. And we’d prefer to know exactly when 443lb ft is going to turn up rather than having to guess.

RIDE & HANDLING

The compliant Alpina B3 Biturbo

It’s not often that a 404bhp BMW feels as mature and considered as this. Many companies would have been forgiven for making this performance saloon super-stiff, but not Alpina. And thankfully, that’s not what it has done; quite the opposite, in fact.

By ladling what must have been some very careful chassis tuning on top of decades of experience of what its customers actually want, it has arrived at a handling compromise to rival the most expert that we can think of.

It's worth ticking the box for the optional limited-slip differential

There are, in effect, two settings for the standard adaptive dampers: Comfort and Sport (Sport+ really only puts the stability control into a slightly freer setting). And on the road – the place where Alpina absolutely intends its cars to be used and judged – the B3 is alert, controlled and engaging, even in Comfort. It turns in with abundant grip and poise and has the 3 Series’ usual clean, uncorrupted directional responses.

Select Sport and the suspension tightens up but hardly ever feels hard, jostling or uncomfortable. Like so many of the best multi-talented and usable fast saloons, the B3 has a chassis that produces body control with fluency and whose dampers respond quickly to rein in float and pitch, but without ramping up to anti-social levels of interference. In other words, the Alpina makes going fast feel easy.

And what results is a superbly rounded car that’ll no more rattle your fillings or trouble your chiropractor than leave you wanting more raw urge. And as Alpina devotees well know, the firm understands how to use those 20-inch alloy wheels without introducing harshness into the ride. There’s some road noise to contend with, but it’s not excessive.

The B3’s steering feels well weighted, and it’s trustworthy and communicative. Like so much else about this car, it’s a pleasure to interact with but never an imposition.

MPG & RUNNING COSTS

Alpina B3

To truly appreciate the new Alpina B3 Biturbo, it’s necessary to distinguish it carefully from BMW’s own extraordinarily gifted 3 Series line-up – hence the substantially higher list price.

It looks expensive if you don't compare it to the M3 to measure up to, especially given that a new 340i or 330d can be had for just over £40k. However, on the road, neither could be considered a match for the B3.

The B3 makes for a relaxed, comfortable motorway cruiser

Both are a country mile behind the Biturbo’s output, and even BMW’s superb 3.0-litre diesel engine is unable to reproduce the almighty tug Alpina has coaxed from its powerplant above 3000rpm.

Extend that line of thinking out to take in the rest of the B3’s rivals and it’s a similar story. An Audi RS4 Avant is in the ballpark but is similarly deficient on torque and not nearly as comfortable.

A Mercedes-AMG C 63 finally outmuscles the B3, as does the defunct Jaguar XFR, but because one has the displacement of an oil drum and the other a supercharger, they chew huge amounts of fuel, while Alpina quotes a deeply impressive 37.2mpg combined. On our touring run we clocked 35.4mpg – some 11mpg better than the Mercedes managed over the same distance.

Underpinning that figure, and trumping everything in sight, is a remarkably low CO2 figure. Emissions may be lower down the buying criteria at this level, but delivering 177g/km means low VED costs. It also renders the B3 a palatable company car option.

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VERDICT

4.5 star Alpina B3 Biturbo

Like the idea of an Alpina? Then this is probably all that you hoped one would be.

The best traditions of Alpina live on within the B3 Biturbo. Its exceptional performance is as subtle as the rest of the car is to sit in and look at, while its ride and handling are all but ideally suited to the car’s mature and relaxed but capable dynamic intent.

Both supple and entertaining in equal measure. Lovely

It feels infused with the character of a tight-knit group of engineers working with passion and enthusiasm for a similarly minded bunch of enthusiasts to enjoy. It feels very European, too, and utterly at home on British roads.

Germans will tell you that many of their local roads are little better than ours. That’s true, and we suspect it is one of the reasons the B3 rides so well.

However, it’s on roads you might think of as typically Germanic – ones that are fast and smooth, or straight and faster still – that the B3 really finds space to excel.

Truth is, a standard 3 Series is already spectacular, but even so, it is easy to relate to the way this Alpina B3 does things. Rapid, rewarding but undemanding cars don’t come much better.

It is, if you like, a sporting car, not a sports car, and all the better for it.

What car new buying red 288

Matt Prior

Matt Prior
Title: Editor-at-large

Matt is Autocar’s lead features writer and presenter, is the main face of Autocar’s YouTube channel, presents the My Week In Cars podcast and has written his weekly column, Tester’s Notes, since 2013.

Matt is an automotive engineer who has been writing and talking about cars since 1997. He joined Autocar in 2005 as deputy road test editor, prior to which he was road test editor and world rally editor for Channel 4’s automotive website, 4Car. 

Into all things engineering and automotive from any era, Matt is as comfortable regularly contributing to sibling titles Move Electric and Classic & Sports Car as he is writing for Autocar. He has a racing licence, and some malfunctioning classic cars and motorbikes.