The BMW X5 M50d goes a long way to revitalise a range that's become a bit long in the tooth.
It's been engineered by BMW's 'M' performance division, and has a 3.0-litre six-cylinder diesel engine that uses three turbochargers to develop a mighty 375bhp and 546lb ft of torque. That's enough power to propel this enormous SUV from 0-62mph in just 5.4 seconds.
What's the 2013 BMW X5 M50d like to drive?
The breathtaking power of the engine, coupled with the immense traction you get from the four-wheel-drive system, makes off-the-mark acceleration feel seriously rapid.
Put your foot down with any purpose while on the move and the car responds with an instant injection of pace. That's partly due to the excellent eight-speed automatic gearbox, which swaps ratios with impressive speed and smoothness, and always selects the best gear for the situation at hand.
However, it's the way the M50d's epic power is delivered that is most interesting. The three turbochargers act sequentially, making the delivery extremely linear over a wide rev range, with no noticeable peaks and troughs. This makes for an effortlessly flexible engine, but it also makes the car feel curiously easygoing.
That's great for those who merely want an extremely fast diesel, but if you're seeking the traditional ferocity and fireworks of an M car, you might be disappointed.
The handling won't disappoint you, though. For a car of this size and weight, the X50d changes direction with incredible crispness and agility thanks to its impressive grip, tight body control and alert steering.
Granted, there's a firmer edge to the ride than you get in most big SUVs, but it rarely becomes irritating and is never uncomfortable.
The engine could sound fruitier when you pile the revs on, but the fact that it's barely ticking over on the motorway makes the M50d a fine cruiser.
Wind noise is well isolated, too, but the wide tyres do produce a fair amount of road noise on coarse surfaces.
What's the 2013 BMW X5 M50d like inside?
The dashboard is clearly laid out, and the iDrive infotainment controller makes it easy to find and use the car's various functions. There's full electric adjustment for the driver's seat and steering column to help you fine-tune your driving position, and all-round visibility is good, too.
There are a few sporty touches in the cabin, such as leather sports seats and brushed aluminium dashboard panels. However, you might think these touches are a little too subtle, because it feels like you could be sitting behind the wheel of any X5.
Still, like all X5s, the M50d has a cabin that feels built to last, made from high-quality materials.
What's more, the cabin is impressively roomy for five adults, and there's a huge boot.
Should I buy one?
If you're after a super-fast SUV that won't bankrupt you at the fuel pumps, the M50d should definitely be near the top of your shortlist.
It's especially impressive that this range-topping diesel engine has the same average economy 37.7mpg as the lower-powered 40d engine, and is only marginally thirstier than the entry-level X5, the 30d.
However, at 60,815, the M50d is not a cheap car. Settling for the 40d will save you almost 13,000, and it's still very fast.
What Car? says...
Engine size 3.0-litre diesel
Price from 60,815
Torque 546lb ft
0-60mph 5.4 seconds
Top speed 155mph
Fuel economy 37.7mpg