BMW X5/X6 M50D review

By: David Morley

Date: 21.12.2012

BMW X5/X6 M50D

BMW X5/X6 M50D

BMW X5/X6 M50D

BMW X5/X6 M50D

BMW X5/X6 M50D

BMW X5/X6 M50D

BMW X5/X6 M50D

BMW X5/X6 M50D

Road test: Tri-turbo is wickedly fast

Test: BMW X5/X6 M50D

BMW X5/X6 M50D

The stats are astonishing: six cylinders, three litres, 280kW, 740Nm, 0-100 in 5.4 seconds, 7.5L/100km and three turbos. Oh, and it’s a BMW.

If you think that sounds like the next hot 3-Series, you’d be wrong because those vitals belong to an SUV. A full-sized SUV. And a diesel SUV at that. We’re talking the new M50d variant of BMW’s X5 and X6.

BMW doesn’t plaster its M badge on cars willy-nilly. So when it applies the big M to a diesel SUV, you better believe there’s some special engineering going on. And special is a pretty apt word for its new tri-turbo oil-burner. We’ve seen the 3.0-litre engine in other BMW SUVs since last year, but this is the first time we’ve sampled the triple-turbo Super Engine (as BMW calls it).

A lighter, alloy crankcase forms the basis of the new engine, but since it has to withstand the stresses of high-compression, turbocharged diesel combustion, the whole thing is held together with the head bolts continuing down to tie into the main bearing caps. The turbo triumvirate (I promised I’d never use that word!) consists of a small turbo with variable geometry that spins up early, followed by a big secondary turbo for mid-range and a third, smaller unit to keep the power coming on strong at the top end. There’s some seriously complicated plumbing and air-flap work going on, too, but it all operates sufficiently for this engine to possibly represent diesel’s best chance of an extended life in passenger cars.

In the 2.15-tonne X6 M50d (the ‘50d’ is to differentiate it from the petrol V8 X6M, which will continue to sell alongside it) the engine is simply amazing. Forget what you thought you knew about diesels – even modern blown ones – because this thing re-writes the book on fast oilers.

The eight-speed auto is perfect for this engine, and progress around town is smooth and quiet. But plant your boot and the M50d simply blasts off. The only problem with overtaking is that you’re likely to be doing lock-me-up speeds by the time you pull back in. Even in taller gears, the engine has so much squirt and such instant response, you’ll swear you’re in a very torquey sports car rather than a 4WD.

It even revs pretty hard (5000rpm is no problem) and on a drive through some hilly country in New Zealand with no real thought for economy, the trip computer showed a remarkable 8.4L/100km average. So not only does this new engine give diesel a shine, it wipes petrol engines off the map for this type of application. Never saw yourself going diesel? Drive this thing and you might be whistling a new tune.

It’s a relative bargain too – undercutting the slightly faster but vastly thirstier petrol Ms by over 30-grand. But the engine won’t make it into right-hook Threes and Fives because the tri-turbos sit where the steering column goes. What a crying shame.

SPECIFICATIONS

BMW X5/X6 M50d

Engine:  2993cc 6cyl, DOHC, 24v, triple-turbo diesel

Power: 280kW @ 4000-4400rpm

Torque: 740Nm @ 2000-3000rpm

Weight: 2150kg

Gearbox: 8-speed automatic

O-100km/h: 5.3sec (X6 – claimed)

Top speed: 250km/h (limited)

Price: $146,500 (X5); $157,000 (X6)

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