These are the new 171mph BMW X5M and X6M super-SUVs – the maddest cars to ever wear the coveted BMW M badge.

Sitting at the top of their respective ranges, both the BMW X5M and BMW X6M share the same 4.4-litre twin-turbocharged engine with identical performance figures.

Thanks to a colossal 555bhp and 501lb/ft of pulling power, these Bavarian brutes will rocket from 0-62mph in 4.7 seconds – the same as the BMW M5 and 0.2 seconds quicker than the BMW M3.

Both models are limited to 155mph, but this can be removed via the optional M driver’s package to give a top speed of 171mph – 2mph less than the Porsche Cayenne Turbo S.

The BMW X5M and X6M both get intelligent all-wheel drive which distributes the appropriate amount of power to each wheel when coming out of a corner.

And as with the all models with the fabled ‘Motorsport’ badge, these two Beemers get ‘M Dynamic Mode’ which adjusts the cars’ traction control, allowing maximum power through the bends.

With MDM activated the 4x4s become rear-wheel drive with BMW stating drivers will be able to drift these 2.4-ton cars.

BMW has employed a pair of 390mm disc brakes with the task of stopping the X5M and X6M’s massive 20-inch front alloy wheels while the rear make do with 380mm discs.

Both models get all the standard M-Power bells and whistles including head-up display and the M badge covered all over the car’s seats, trim and body panels – along with the all-important four exhaust pipes, an essential for a BMW M car.

As with all BMWs, the X5M and X6M both get EfficientDynamics to help give these 171mph M models a respectable level of greenness.

This means 320g/km of carbon dioxide and an average fuel consumption of 20.5mpg, although we’d imagine any ‘excitable’ driving will result in a sub-10mpg figure.

On the face of it, these numbers aren’t the most impressive but they sit head and shoulders above the 510bhp Mercedes ML63 AMG which emits 392g/km and averages 17.1mpg.

The BMW X5M and BMW X6M will arrive in UK showrooms in October with prices for the super-SUVs to be announced closer to the date.

BMW X5M and X6M: Brilliant - but the wrong M cars?