What is it?
The BMW X5 M50d is proof that, contrary to popular belief, four into six goes just fine. Suggest that to your primary school teacher and you’ll probably earn yourself some extra homework. Say it to a BMW powertrain engineer, however, and he’ll just nod and smile wryly.
In fact, when four turbochargers are forcing compressed air into the six inline cylinders of the BMW X5 M50d’s diesel engine, there is much that seems to go – and go rather well. This car is the M Performance ‘caretaker boss’ of Munich’s new fourth-generation X5 range, all set to be in charge until the M division lets loose another equally regrettable and inevitable X5 M wide boy.
The M50d’s engine develops 395bhp and 561lb ft. It’s a way off matching the headline figures of what every road tester will feel duty-bound to acknowledge as its mortal rival, the Audi SQ7 – not that many of the M50d’s likely BMW devotee owners, who would probably sooner set light to their annual bonus than spend it on an Audi, will much care.
What’s much more interesting is that BMW is sticking to its guns and continuing to back a high-performance diesel engine for this car, after Porsche has abandoned them entirely and is preferring, along with the likes of Land Rover and Volvo, to look to high-output plug-in hybrids in this kind of SUV.
There will, of course, be a new X5 ‘PHEV’ along in due course, too; but it won’t be positioned at a like-for-like level as the M50d in X5 model hierarchy. Which probably tells you at least as much about the maturing that BMW thinks its hybrid powertrain technology still needs to do as it does about how stubbornly Munich may be inclined to hold onto its long-nurtured performance diesel engine technology lead.