BMW’s M division isn’t blasé about its heritage. It was a very big deal for it to change to all-wheel drive for the sixth-generation M5 sports saloon, a decision that was not taken at all lightly. Frank van Meel, BMW M boss, told us that he brought senior management out for a test in an early engineering prototype to convince the powers that be it was the right way to go, and even now, at our first opportunity to drive the finished article, he tells us that it’s “not an all-wheel-drive car, but a rear-wheel-drive one with added traction.”

Backing up van Meel’s claims, and calming BMW M car rear-drive diehards somewhat, is a mouth-watering technical specification with the new ‘M xDrive’ four-wheel-drive system at its centre. This is quite different to that in the likes of the BMW X5M and X6M. For starters, there’s an Active M differential on the rear axle as on all rear-drive M cars of the last few years. This is electronically controlled and can vary the side-to-side lock-up from zero to 100 per cent. It now features carbon plates too, said to smoothen out its reactions and make it easier for the driver to feel what’s going on, giving the car a more natural feel.

The front axle makes do with an open differential, while a transfer case (using an electromechanically activated multi-plate clutch) is responsible for splitting the engine output between the front and rear axles. Controlling all of this, and interfacing with the Dynamic Stability Control (DSC), is a brand new electronic box of tricks that is unique to BMW M and referred to simply as the ‘dynamics control unit’. BMW doesn’t quote target splits between the front and rear wheels, but instead aims to give the driver a typical M car rear-driven feel and hence the split is altered on the go depending on conditions. Crucially, the driver can influence that by accessing the new M xDrive menu.

The two M buttons can be programmed to alter the steering, throttle calibration and damping exactly the way you want those to be

On start-up, the M5 defaults into ‘4WD’ mode, with DSC turned on. It still feels remarkably rear-led in this guise, though if you push hard on the exit of a corner you can sense torque being sent forward to help the car straighten up. Nonetheless, it never easily washes into understeer and, in slippery conditions, you can get on the power nice and early and leave the car sort out the traction for you. This is a big change for a modern M5, which have all been severely traction limited in poor conditions, making the uninitiated a little nervous of them. This car eradicates that characteristic.

Thankfully, that’s not the only trick up its sleeve. For starters, tap the DSC button once and the M Dynamic Mode is switched on (meaning more relaxed stability control intervention), as is the ‘4WD Sport’ setting. The M5 is noticeably more rear-driven in this guise and it’s a riot, allowing you to take plenty of liberties into, through and out of a corner. It even allows a few degrees of slip at the rear and the DSC involvement is virtually non-existent in the dry. We’d like to see this as the default mode.

But to truly unlock the new M5’s potential you need to hold the DSC button down for longer until it is switched off completely. Then the driver can choose from 4WD, 4WD Sport or 2WD. The latter allows those with more experience (and/or access to a track) to experience the new M5 as a purely rear-wheel-drive car, with zero assistance from DSC. Somewhat surprisingly, BMW has managed to make the new M5 easier to drive fast in this guise than the old one, with the limits of adhesion more clearly telegraphed. Apparently that’s thanks to the rear differential changes Nonetheless, only a small percentage of M5 owners are likely to use this mode regularly, which is why it’s such a joy to discover that the best setting is DSC off with 4WD Sport. This enables full drifts if space and talent allows, but much more than that it gives the M5 a deliciously agile feel through a sequence of corners and you sense that the car can use all the available power to the full, even if you’re not a professional race driver. Shame that the steering, while well-weighted and direct enough, is lacking much in the way of feedback.

The 4.4-litre V8 has been upgraded and is brilliant across the rev range

In all the focus on the M xDrive system, it’s easy to forget that the twin-turbocharged 4.4-litre V8 engine has been upgraded a tad, too, and it kicks hard from anywhere in the rev range, even if it isn’t as sonorous as we’d like and it relies on electronic augmentation to sound sporty inside the cabin. It’s now mated to an eight-speed automatic, which is simply perfect most of the time, regardless of the settings you choose for it (a chunky new shifter on the centre console features a three-mode toggle switch for the Drivelogic system). And as ever in a BMW M car, there are dozens of combinations of driving settings to choose from when altering the power steering, throttle calibration and damping, altering the M5’s personality from refined cruiser to hard-edged sports saloon in a moment. Two groups of settings can be programmed into the bright red M1/M2 steering wheel buttons, which sit on a lovely new round steering wheel with gearchange paddles and unique digital instrumentation behind. The rest of the cabin is a restrained take on the current 5 Series with loads of equipment and technology as standard and fantastic seats.

Thanks in part to those red buttons (a finish that is echoed in the engine start button), the new M5’s interior is a little more special looking than before, while the exterior gains a carbon fibre roof for the first time. The rest of the bodywork is subtly more muscled and features bespoke 20-inch wheels and door mirrors, a wider track and a little boot lip spoiler. Not the mention the requisite quad exhaust outlets. So yes, things have changed, but we think you’ll agree with us when we say it’s very much for the better and very much a BMW M5. And we’re not being blasé about that in the least.