BMW X5 M50d.

BMW X5 M50d.

Ten years ago you would have been laughed out of town if you'd suggested BMW would have built an SUV wearing an M (its famous high performance and motorsport division – M GmbH) badge and powered by a diesel engine; a triple-turbocharged diesel engine no less.

In the recent past if you wanted a performance SUV you needed a petrol-guzzling V8 engine. Not now though. The rise in popularity of both genuinely sporty Sports Utility Vehicles and performance-orientated diesel engines cannot be denied. And running your eyes down the specification sheet it's hard to argue with the raw numbers.

There's 280kW of power, a whopping 740Nm of torque, a 0-100km/h sprint in just 5.4 seconds and a claimed fuel consumption figure of just 7.5 litres per 100km for all that performance.

The M50d builds speed faster than the V8 petrol-powered xDrive50i which boasts 300kW and 600Nm and does 0-100km/h in 5.5 seconds; that's not much slower, but it's still slower.

In the real world one squeeze of the accelerator is enough to make you a convert. It has effortless pulling power thanks to the three turbos that work sequentially to try and eliminate the lag associated with turbocharged engines. Peak torque – or pulling power – kicks in at just 2000rpm.

That much torque makes taking off from the lights and overtaking a breeze, despite the X5's considerable size.

But what about the diesel's biggest hurdle in winning petrol lovers over; the noise? Well, if you have the windows down there's no mistaking the 50d for anything other than a diesel. It doesn't sound like a tractor but there is the unmistakable diesel "chug".

Keep the windows up, however, and the 50d produces a purposeful rumble from beneath the bonnet that has a unique charm.

It is paired with the standard eight-speed automatic transmission that is able to make good use of the flexible engine.

It may not drink petrol but in almost every respect the triple-turbo six-cylinder engine lives up to the famous "M" badge on its bootlid.

But, strictly speaking, it's not an M model, it is part of the new “M Performance” range that BMW is beginning to spread across its range. In a nutshell that means performance parts (both under the skin and on the surface), but without being a full-blooded performance machine.

The X5 M50d, and its sibling the X6 M50d, get M tuned suspension, a unique aerodynamic bodykit and a sporty steering tune.

The suspension does a good job of trying to make the M50d feel sporty but there is no disguising this is a big SUV – not a sports car. Having said that, the X5 remains one of the most enjoyable and engaging SUVs to drive on the market.

Other unique features for the 50d include 20-inch alloy wheels, Sports seats, Alcantara and leather interior and seat trim, "M" leather steering wheel with paddle shifters, "M" door sills and roof rails.

Standard equipment, which it shares with the 50i over the rest of the X5 range, includes four-zone airconditioning, adaptive bi-Xenon headlights and self-levelling suspension.

The Alcantara on the seats and other parts of the trim help to give the cabin a sporty feel, but the rest of the interior – especially the dashboard – feel like standard X5 fare. In other words, a bit plain for a car that costs $147,500. That's more than $33,000 more expensive than the next cheapest diesel; the xDrive40d.

It's also worth pointing out that the M50d is also $13,000 pricier than the 50i; which buys you a lot of petrol.

Ultimately the M50d is an impressive car but whether it is worth the extra spend over a 40d or a 50i is a decision that rests with the buyer.

What isn't in question is just how far diesel engines have come in the past decade.

Vital statistics

On sale Now
Price $147,500
Engine 3.0-litre triple-turbo six-cylinder turbo diesel
Power 280kW
Torque 740Nm
Transmission Eight-speed automatic
Fuel consumption 7.5L/100km