Does affixing an “M” to the peak model in the 7 Series range transform it into the super-saloon that’s never been? Almost, but not quite…

No other series-production BMW in the German company’s 101-year history has been as powerful, nor accelerated with as much venom (well, before the recent reveal of the new 441 kW M5, anyway), says the carmaker. Somewhat ironically, for the time being, this title belongs to the saloon in the brand’s stable that’s least associated with sporting prowess.

Yet, here we are on our test strip and the 2,3-tonne M760Li has just posted a 3,96-second 0-100 km/h sprint time. The M4 GTS managed a comparatively pedestrian 4,42. Closer, but still no match, the outgoing M5 Competition needed 4,10 seconds. BMW’s i8 hybrid sportscar? A “middling” 4,36 seconds.

We have no reason to dispute BMW’s claim. The M760Li clocks a number of other firsts on its way to steamrolling all its range mates into submission. The 6,6-litre V12 engine is the first powertrain in the M Performance fold with a dozen cylinders. Boasting an all-aluminium block, new high-pressure injection system and a recalibrated double Vanos continuously variable camshaft-timing system, the Rolls-Royce Wraith-shared unit develops 448 kW at 5 500 r/min and 800 N.m from 1 550 r/min.

Thanks to two mono-scroll turbochargers – here positioned on the outside of the two rows of cylinders and instantly supplying each bank with compressed air – that plateau of torque is sustained all the way to 5 000 r/min, from where it gently tapers off towards the 7 000 r/min red line. Linked to the V12 is an M Performance-tweaked eight-speed torque-converter automatic transmission that directs power delivery to the first-for-South-Africa xDrive all-wheel-drive system that’s rear-biased, but which is able to increase the torque flow to the front axle by up to 50% of full capacity.

According to BMW, only three years ago, a powertrain with this much oomph would not have been possible in a similar car because the rear axle would have been unable to cope with such high levels of torque. Thankfully, xDrive makes it possible to engineer 800 N.m to reach the tarmac without shredding metal in the process (although, it’s interesting to note, Mercedes-Benz has been sending 1 000 N.m to rear axles for years without reports of catastrophic failures).

These three elements – stonking great powertrain; flawless transmission; grippy all-wheel-drive system – utterly define the M760Li’s on-road ability. The engine feels incredibly strong, but perhaps not quite in the way you’d imagine. Unlike the AMG S63’s livewire V8, for example, the V12 needs generous servings of throttle travel before clearing its throat, hiking up the vast nose and bellowing to that 7k redline. Keep the throttle pinned as you sink deeper into the multi-way-adjustable Comfort seats and it picks up momentum like few large sedans we’ve experienced; one exception being the Porsche Panamera Turbo we recently tested.

In the Seven, 80 to 120 km/h is done and dusted in a mere 2,42 seconds versus the Porsche’s 2,23 (for reference, the S63 needed 2,55 and the S65 2,58). Performing solid supporting work is the eight-speed torque-converter, which shifts up quickly to top gear when the Executive Drive Pro drivetrain management system is set to comfort or the even more languid comfort+, but keeps a hold of gears when sport is selected. It even makes use of sat-nav data to select the right ratio for inclines, declines and so on.

Sport mode also liberates an additional decibel or three from the quad exhaust pipes, but we’re talking incremental changes here. Thanks to their inherent silkiness, V12s can be quite delicate-sounding engines, lacking the bombast of a V8 or V10, and this 6,6-litre is equally reticent. That said, the sound that’s produced by the standard-fitment M sports exhaust system – drip-fed, in typical BMW style, into the cabin through the 16-speaker Bowers & Wilkins audio system (itself equipped with a number of technologies necessitating an ® suffix) – is cultured and multi-layered, plateauing from a burbly idle into a subdued howl as the flaps open wide.

So far, so wonderfully indulgent. But how does this behemoth fare in the corners, the ultimate proving ground for BMWs studded with M badges? The M760Li’s spec document (a match in scope for the first draft of a sweeping novel) lists a raft of systems and settings coupled to Executive Drive Pro to make 2,3 tonnes attack bends with real gusto and not simply reserved tolerance. Chief among them are active roll stabilisation in the form of Dynamic Damper Control that keeps the body flat, as well as Integral Active Steering that steers the rear wheels in the same or opposite direction as the front ones to increase agility, or aid stability.

Ultimately, these computer-controlled functions allow the M760Li to carry great speeds through bends, all the while feeling settled until the front-end starts pushing wide and the tyres protest. The body stays remarkably flat, the air-suspension swallows mid-corner bumps whole and the steering remains uncorrupted and direct. But, it doesn’t feel that much different to any normal 7 Series…

There’s very little pleasure to be had in pushing the M760Li past its very obvious (but, admittedly, lofty) limits. The 2,2-turn lock-to-lock electric steering ultimately lacks any real sensitivity and can, at times, feel aloof when it should be plugged in. Switch off the traction control, which you can do fully, and that rear-biased torque distribution permits the rear axle to slip ever so slightly before the xDrive system neatly reins it all in.

Oddly, a number of testers noticed some squirming under hard braking, especially during one testing stint putting the Big Beemer through its paces on the nuggety surface of Dutoitskloof Pass. The craggy tar saw the M760Li struggle to maintain composure as the four-piston front callipers bit down hard on the vented discs. Later that week during our punishing 10-stop emergency braking testing, the BMW posted an average stopping time from 100 km/h of 3,09 seconds, which earns it a “good” rather than “excellent” rating.