With the Porsche Cayenne Turbo and Mercedes-Benz ML 63 AMG in their dual sights, the X6 M will be priced from $179,900 (plus on-road costs), while the more practical X5 M will cost $172,900 (plus).
Sitting at the top of the X6 range, the X6 M is powered by a 4.4 litre twin-turbocharged V8 engine - the same powerplant that propels the X5 M.
Peak power is a hefty 408kW in the X5 M, and torque tops 680Nm.
Despite its mass, the big X5 M can sprint from zero to 100km/h in just 4.7 seconds, and top speed is electronically limited to 250km/h.
Power output and 0-100km times for both cars better those of the Cayenne Turbo S and Mercedes ML 63 AMG, while their pricing puts them within striking distance of the Benz and significantly under the $275,000+ Porsche.
With the X6 range outselling the Cayenne earlier this year (so far 734 X6s have been delivered), BMW has high hopes that well-heeled buyers will respond positively to the presence of a new performance flagship in the line-up.
"Many X6 customers are entrepreneurs or self employed professionals with one or no kids, and new to the BMW brand," Stavros Yallouridis, Head of BMW Australia said.
"They told us that traditional SUV styling was boring and normal coupes offered less versatility than the X6.
"Now with the arrival of the X6 M, we're able to offer an M version which will tempt performance-oriented buyers considering an ML 63 AMG or Cayenne Turbo with benefits such as faster acceleration, less weight and better fuel consumption."