Famed BMW tuner's diesel take on the latest 4 Series could represent the zenith of the executive cruiser

Germany’s classic executive saloon has hit something of a zenith with this extra-special version of the BMW 4 Series Gran Coupé.

The BMW Alpina D4 S Gran Coupé has a super-rare combination of static, dynamic, rational and subjective qualities the likes of which you only find in cars built for uncompromising speed, efficiency, luxury, desirability and driver appeal. Cars that just don’t take no for an answer.

Our test car’s Ivory White extended Merino leather felt great and looked lavish and sophisticated, but Alpina still finds a place for its trademark blue-and-green coloured stitching around the inner steering wheel rim.

The D4 S seems, to me at least, like the manifestation of so many things that the European luxury car industry has worked tirelessly in pursuit of and made countless marginal gains on over the past half-century. It’s fast and frugal, effortless and opulent, refined and exclusive, enticing to travel in and engaging to drive. 

But above all else, it’s a sensational long-distance car. And in another 15 or 20 years, when we may very well be defaulting to high-speed trains when we have more than 100 miles to travel, will we even remember that its like ever existed, I wonder? Will we know what we’ve lost? The electric car may be good at lots of things, but I don’t suppose it will ever decimate distance with the supreme ease of a D4 S.

The past couple of years for celebrated (but no longer independent) BMW tuner Alpina have been mostly about its respective takes on the G20 and G21 generations of the 3 Series, but it announced its six-cylinder petrol and diesel takes on the current G26-generation 4 Series four-door grand tourer in spring 2022 - and now both are around in the UK in right-hand drive form. 

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Alpina d4 s gran coupe 03 back cornering

The B4 uses the 3.0-litre turbocharged petrol straight six that you will also find in the latest B3 saloon and B3 Touring; while the D4 S we’re testing here adopts the 3.0-litre twin-turbocharged diesel straight six from the equivalent D3 S.

Thanks to Alpina’s usual under-bonnet fettling and boosted cooling measures, it produces 350bhp (a 10% boost on what you would get in the BMW M440d, although that doesn't come as a four-door) and 538lb ft of torque.

Torque-vectoring xDrive four-wheel drive is standard, ditto an eight-speed automatic gearbox - and Alpina offers its own suspension and steering tuning, and its own lavish interior specification, of course.

Fast diesels were doing big business for Alpina in Britain only a few years ago, so the Dieselgate fallout must have been a significant factor in the firm’s decision-making process when it finally sold control to the BMW mothership. For a small outfit like this, simply not knowing which engines to invest in must have been suffocating. Take the wrong risk and the family business is in dire straights.

Well, they did alright to invest in this one. Fashionable or not, the D4 S’s diesel six is commendably smooth and quiet, with that wonderful tidal surge of accessible torque right under your toe. It’s nice to listen to; it keeps revving beyond 4000rpm when you need it to; and it makes for a near-two-tonne BMW with abundant real-world pace.

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Alpina d4 s gran coupe 11 dashboard

And yet the greatest recognition I can pay to this monumental powertrain is to note that, at a UK-typical 65-75mph motorway cruising speed, it will return 53mpg - and cover 650 miles on its 59-litre tank. This is a 168mph car, let’s not forget, capable of 62mph from rest in less than 5.0sec. At faster German autobahn cruising speeds of 120-140mph, it’s reasonable to imagine that it would still do 35mpg and give you 400 miles between refills; at speeds at which an equivalent petrol performance saloon might only be doing 20mpg and an EV - pretty much any EV, really - would drain its battery flat inside of 80 miles.

The D4 S’s suspension and steering tuning make it ideally comfortable and secure – and quiet-riding, too – at a fast cruise but also balanced and rewarding during more enthusiastic moments. You get just a hint of its weight and its touring agenda on cross-country roads with bigger vertical inputs. But for steering feedback, turn-in incisiveness and outright handling balance, Alpina’s particular choices on wheel geometry, anti-roll bar specification and fitted tyre come together beautifully. The D4 S has enticing tactile feedback and tangible cornering poise that elevate it significantly beyond the reach of any M-sport BMW for driver appeal.

If there's to be any justice about the way that electrification takes its axe to Europe’s ICE luxury model ranks over the next few years, cars like this will be the last left standing. There won’t be, of course (and who knows what Alpina’s business will look like in another five years’ time?). But the D4 S richly deserves to endure.

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Alpina d4 s gran coupe 04 side panning

Matt Saunders

Matt Saunders Autocar
Title: Road test editor

As Autocar’s chief car tester and reviewer, it’s Matt’s job to ensure the quality, objectivity, relevance and rigour of the entirety of Autocar’s reviews output, as well contributing a great many detailed road tests, group tests and drive reviews himself.

Matt has been an Autocar staffer since the autumn of 2003, and has been lucky enough to work alongside some of the magazine’s best-known writers and contributors over that time. He served as staff writer, features editor, assistant editor and digital editor, before joining the road test desk in 2011.

Since then he’s driven, measured, lap-timed, figured, and reported on cars as varied as the Bugatti Veyron, Rolls-Royce PhantomTesla RoadsterAriel Hipercar, Tata Nano, McLaren SennaRenault Twizy and Toyota Mirai. Among his wider personal highlights of the job have been covering Sebastien Loeb’s record-breaking run at Pikes Peak in 2013; doing 190mph on derestricted German autobahn in a Brabus Rocket; and driving McLaren’s legendary ‘XP5’ F1 prototype. His own car is a trusty Mazda CX-5.