The German carmaker is trumpeting the new mill as the world's most powerful volume-produced six-cylinder diesel engine, delivering 280kW at 4000rpm and a huge 740Nm of torque between 2000-3000rpm.
Those figures represent a 55kW and 140Nm hike over the existing xDrive40d SUVs, and with a number of handling upgrades in the mix, there's little disputing that these are the new flagship models.
Matched with an eight-speed automatic Sports transmission and BMW's xDrive all-wheel-drive system, BMW promises a 0-100km/h time of 5.4 seconds for the X5 M50d, and 5.3 seconds for the X6 M50d.
Fuel consumption and emissions in the X5 version are listed at 7.5 l/100km and 199g/km, while the X6 lists 7.7 l/100km and 204g/km.
While these two M Performance diesels fall short of their petrol M car counterparts in the acceleration stakes, the much lower fuel consumption should prove appealing to buyers looking to strike a balance between guts on the road and pain at the bowser.
Other upgrades for both cars include an enhanced bodyshell and powertrain mountings, along with revised Servotronic mapping for the hydraulic steering setup.
BMW's M division has also modified the electronically-controlled dampers and active anti-roll function in the Adaptive Drive system - the latter standard with the X6 M50d and optional with the family-focused X5 M50d.
Visual tweaks for the two diesel Ms include updated front bumprs with large air intakes and a 'Ferric Grey' metallic finish to the horizontal trim bars.
The mirror caps are also finished in Ferric Grey, and there's 20-inch light-alloy wheels, V8-styled tailpipes and, for the X6, the M powerdome can be spied on the bonnet.
Updates to the rest of the X6 range include subtly revised styling, along with updated specifications that include five seats and internet connectivity both as standard, along with adaptive LED headlights and the powerbulged bonnet for the X6 M.
Depending on the variant, the upgrade brings a price hike to each model of around $1000.
Pricing from April Production
- X5 xDrive M50d - $147,000
- X6 xDrive 30d - $110,900
- X6 xDrive 35i - $121,000
- X6 xDrive 40d - $127,400
- X6 xDrive 50i - $150,400
- X6 xDrive M50d - $157,000
- X6 M - $190,900
Available from June 2012.
Note: prices are Manufacturer's List Price and do not include dealer delivery or on-road costs.
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