BMW’S most powerful diesel engine has landed behind the kidney grille of a facelifted X6 SUV range, ready to kick a little sand in the face of petrol rivals such as the Porsche Cayenne GTS.

Even though the 2.2-tonne X6 M50d is armed with only a 3.0-litre inline six, its triple-turbo technology and mountainous 740Nm of torque helps it to thump down a zero-to-100km/h sprint time of 5.3 seconds – 0.4 seconds faster than the new V8 Cayenne.

The arrival of the new powertrain in the slope-backed X6 – and current X5 – also marks the Australian debut of the Munich manufacturer’s M Performance Automobiles range of sports-enhanced vehicles.

M Performance is a sort of M ‘lite’ – a cross between the standard BMW range and the hard-edged M cars such as the X6 M, M3 and M5.

You can expect more of these M Performance models as new BMW vehicles arrive in Australia, giving punters an opportunity to move up to an M badge at a more humble price.

In the case of the $157,000 (plus on-road costs) X6 xDrive M50d, buyers pay a premium of almost $30,000 over the X6 40d, but save $33,900 over the full-house petrol V8 X6 M.

BMW describes the 280kW M50d diesel engine in the X6 and X5 as the world’s most powerful inline six-cylinder diesel, delivering an extra 100kW of power and 200Nm of torque over BMW’s previous most hairy-chested diesel six, the 180kW/540Nm 30d offered in models such as the 7 Series, X6 and X5.

However, the M50d is not the most powerful diesel SUV in the land – that honour goes to the 6.0-litre Audi Q7 V12 TDI , which stretches the dyno with 368kW of power and 1000Nm of torque.

The BMW diesel derives its extra mumbo from a trip to BMW M GmbH – the propeller brand’s acclaimed high-performance division in Germany – where it gained a couple of extra turbos and other tweaks, such as a new, higher-pressure common-rail fuel-injection system.

In a world first, the blower system combines two small high-pressure turbos with a larger, low-pressure unit, all working in a concert to achieve higher performance across the rev range.

Peak torque is achieved at just 1500rpm and maintained to 3000rpm. Above that, peak power comes on at 4000rpm, with the engine revving all the way to a lofty (for a diesel) 5400rpm.

To handle the extra performance, M engineers have beefed up the engine’s internals. As well, the 2200-bar fuel pressure in the common rail is so intense that it has been fashioned from forged stainless steel.

The engine drives all four wheels via an eight-speed automatic transmission, employing two shift modes – a standard ‘D’ mode and ‘S’ for sports shifts.

As well, the driver can select a ‘manual’ shift mode, changing gears with paddles on the steering wheel or gear-selection lever.

Despite its performance credentials, the X6 M50d achieves an official combined fuel economy test result of a thrifty 7.7 litres per 100km – not far behind the X6 40d’s 7.5L/100km.

Carbon dioxide emissions are said to be 204 grams per kilometre – less than a V6 petrol Holden Commodore and 50 per cent less than the petrol X6 M (325g/km).

The M50d version of the X6 gets an M-spec chassis package, including electronically controlled dampers, air suspension with self-levelling at the rear, special mapping for the hydraulic steering and bigger brakes with 385mm discs up front and 345mm discs at the rear.

The Adaptive Drive suspension package includes an anti-roll function, while the alloy wheels move up from 19 inch to 20-inch alloy units, like those on the X6 M.

The X6’s usual fog lights make way for air intakes to cool the brakes on the M50d.

The trademark BMW kidney grille gets titanium-coloured bars and other subtle touches such as grey exterior mirror caps and big-bore exhaust tips, to set it apart from standard fare.

Inside, the M Performance theme continues with special M sports seats cloaked in a mix of black Alcantara and Nappa leather, all with contrasting white stitching. The seats get the M logo, as does the gear knob and side sills, while the steering wheel is upgrade to an M leather wheel.

The new X6 M50d is part of the mid-life facelift – or “lifecycle impulse” in BMW-speak – for the “world’s first sports activity vehicle” that made its controversial debut in 2008.

Although most of the changes are superficial, one significant departure from the original is the rear seat, which now holds three people instead of two.

BMW says the sporty two-pew rear seat was a deal-breaker for many families considering an X6 in the past, and that the new rear bench will therefore open the vehicle to more potential buyers.

The front fascia has been re-moulded for a more sculpted appearance, while the flagship X6 M gets segment-first active LED lamps – an optional extra on other X6 variants.

The X6 M50d and X6 M both gain a bulging “power dome” bonnet – also an option for other X6 buyers wanting to look the part.

The X range now comprises six models, ranging from the xDrive 30d at $110,900 to the flagship X6 M at $190,900.

All X6 variants cop a $1000 price rise over the superseded range, except for the X6 M that goes up by $5400.

Although the related BMW X5 had its facelift last year, it also gets the new M50d diesel variant with M Performance treatment at $147,000 – $10,000 cheaper than the X6 equivalent.