WHEN it's M treatment time for the BMW many regard as the finest executive car on the market, fireworks are guaranteed.
Festooned with technology including a sports-tuned all-wheel-drive set up and an automatic transmission, the new BMW M5 is the quickest Beemer ever to take to the road.
We got to grips with the sixth generation of BMW's mighty muscle machine at the Anglesey Circuit in North Wales and on the roads of Snowdonia where it showed its credentials in no uncertain terms.
Powered by a 4.4-litre twin-turbo V8 developing 600bhp - that's 48 more horsepower than the previous model - the new M5 has a blistering 0 to 60 acceleration time of 3.4 seconds.
Unfettered, it's good for 190mph and with 700Nm of torque to boot there's power aplenty.
In everyday set up the M5 is restricted to 155mph and under all circumstances this is a car to savour. It's little surprise that it has just been voted the finest performance car on the planet in the World Car of the Year awards.
The soundtrack is a delight and with the active sports exhaust engaged the note from the four tailpipes crescendos in stupendous fashion.
From burble to thunder it's one of a host of electronic enhancements that enables the new M5 to delight at all levels.
With a combination of no less than nine drive modes to go at the M5 can be configured for virtually every driving scenario - from touring to track.
There are three suspension settings - comfort, sport and a firm sport plus - three gearshift patterns and three set ups for the drivetrain enabling the car to be switched from four-wheel-drive to pure rear-wheel-drive if wanted.
Left to its own devices, drive to the front is brought into play only when the rear wheels reach the limits of adhesion.
The result is maximum grip at all times with a splendid degree of suppleness and agility that endows the M5 with a feel of absolute confidence.
Two red M buttons next to the paddle shifters on the steering wheel allow for favourite configurations to be deployed instantly, snapping the car into life.
Particularly impressive was the logic of the gearbox which second guessed the right gear at the right time with uncanny precision. Not once was it lacking, either on the track or on the road.
The new M5 is the first to come with an auto transmission and all-wheel-drive and they have done nothing to diminish the characteristics of BMW's 5 Series flagship.
With snow still lying on some of the high Welsh mountain roads the extra grip proved invaluable when conditions turned slippery.
The combination has had little impact on fuel economy either and we managed to average 26.6 to the gallon over several hundred miles - almost smack on the official rating of 27mpg with emissions of 241 g/km.
It's some two inches longer than previous M5, slightly wider and higher but weighs in 25 kilos less at 1.855 tonnes thanks to the use of aluminium in the bonnet and wings and a roof made from carbon fibre reinforced plastic.
The awesome firepower of the M5 is contained within some conservative styling. Apart from M5 badges on the grille and boot, air vents on the front wings and slightly pronounced haunches the main difference is at the rear where the quad exhausts are separated by a black diffuser.
BMW's trademark black window surrounds reserved for its M models are another feature and the M5 sits on 20-inch alloys while ultra-bright adaptive LED headlamps are standard fit.
Inside, the cockpit is trimmed to the highest standard - almost incongruous luxury for a car with such might - with body-hugging leather clad sports seats complete with illuminated M5 badges.
At night the interior is bathed in a glowing ambient light, highlighted with spiral patterns from within the door-mounted audio speakers.
From a practical perspective it is as accommodating as any other 5 Series with plenty of room front and back and a 530 litre boot making it an ample tourer.
The car we sampled also came with the likes of a head-up display, seat ventilation, soft-close doors and ceramic brakes for added stopping power - all of which took its list price of Â£87,160 up to a heady Â£104,805.
That's a premium price in anyone's book - but then the BMW M5 is the finest performance car in the world and that's official.