Inside the X6 M that I tested was a beautiful, ully optioned cabin that boasted gripping sportseatsand BMW's wide, asy-to-read infotainment screen. The leather-wrapped everything and carbon-fiber trim were both well executed, nd my hands rejoiced at the feeling of the thick-rimmed, erious-looking steering wheel.The most impactful changes aren't visual but visceral. The X6 M's turbocharged 4.4-liter V8 now puts out 567 horsepower and 553 pound-feet of torque – up from 555 hp and 500 lb-ft in last year's model. BMW has also replaced the six-speed automatic gearbox for an eight-speed Steptronic auto, elping the all-wheel drivetrain (now with more of an inclination towards the rear) to get the car to 60 miles per hour in four seconds flat.Out on the road – from hard starts just for shits and giggles, nd while passing steer-haulers and stake trucks with just a whisper of throttle – the effect of all that power is immense. Driving for a couple of hours, he silky smooth power delivery via that eight speed transmission and the great gobs of torque it was serving up made the hefty Bimmer feel surprisingly light on its feet.With low noise, ibration and harshness and such a persuasive powertrain, ou'd think the X6 M would be a dreamboat for cruising and the occasional blast of ridiculous speed, nd you'd be right, f only the switch to electrically assisted steering didn't make piloting the thing so disconcerting.