Buchloe-fettled cars have always been a more relaxed, less hyperactive proposition than their BMW cousins, so the choice of 3.0-litre twin- turbo diesel for Alpina's latest offering, the D5 Biturbo, seems entirely apt.
535d, and then some
Based on the 313hp, 464lb ft 535d, the new D5 brings an extra 37hp and 52lb ft of torque to the party, and yet somehow managing to post mpg figures and emissions that are identical to the far more humble 530d.
Ask for a bit of acceleration and, after a pause to allow the turbos to spool up, the D5 fairly leaps down the road, allowing you to ride the fat torque curve and pile on speed at quite rate. OK, so it's not M5-explosive, but it is darn fast, and although it will rev out to 5,000 rpm or so, you really don't need to do so to make vigorous progress. Mind you, if you start plumbing the depths of that torque on a regular basis it will start to hurt the fuel economy quite heavily. But it's just so satisfying... particularly in combination with the Alpina-tuned 8-speed ZF Switchtronic transmission
The D5 is more than just a tweaked turbodiesel, however. The Alpina styling tweaks to the F10 5 Series (skirts, rear spoiler, 'those' wheels, front bumper, decals, and as much or as little bespoke interior work as your wallet can manage) might be an acquired taste, but I guarantee Alpina's work to the chassis will be of more universal appeal.
Put simply, the D5 manages to work with the UK's pockmarked road network better than any current BMW. It's more fluid, more controlled and a more involving steer. It works with the road rather than despite it. This can be partly accounted for by the fitment of non run-flat tyres, but the work done to the electronic dampers must surely take most of the credit. Provided you don't put them in too soft a setting, that is - Comfort and Comfort Plus are just a bit too 'floaty'.
That 5 Series size issue again...
It's not all good news, of course. On smaller British roads the F10 body shape still feels half a size too large (whether it actually is or not is kind of a moot point; it feels as though it is), and that engine does lack the precision and zing that the true petrolhead will crave.
In comparison with BMW's new and super-tricksy tri-turbo diesel, the D5 also seems a teensy-bit lo-fi. Then again, BMW isn't bringing the M550d to the UK (more on this on the blog), leaving us only the unlovely X6 and chunky X5 with which to sample its new engine. Which gives the D5 the super-fast diesel BMW market pretty much all to itself.
Worth every penny? Depends whether or not you can stomach a diesel. If you can, we reckon the Alpina D5 is an absolute gem, a car that, even if it did have a rival, it would be hard to imagine it being anything other than the top of its class...
ALPINA D5 BITURBO
Engine: 2,993cc straight-six, twin-turbo
Transmission:8-speed auto, rear-wheel drive
Torque (lb ft):516@1,500-3,000rpm
0-62mph: 5.1 sec
Top speed: 171mph
MPG: 47.9mpg (combined)
Price: £55,950 (£63,410 as tested)