Estoril, Portugal - You have to wonder why such an obvious solution hasn’t happened sooner. If offroad vehicles can have switchable transfer cases to send drive to either one or both axles depending on traction necessities, why can’t high performance passenger cars?

Here’s the deal: brands like BMW which pride themselves on driver engagement and balanced handling (both politically correct ways of saying driftworthiness) have found themselves in a bit of a conundrum in recent years, where rear-wheel drive isn’t really effective at coping with such absurd power outputs anymore.

Take the now discontinued fifth generation M5 for example. We spent around 10 000km with one on long-term test, and a good portion of that distance was spent with the traction control light flickering.

And that car had “only” 423kW and 680Nm. The new sixth generation model launched to the world in Portugal last week is tuned to an all-time M5 high of 441kW and 750Nm.

That’s enough oomph to have stability control systems suffering constant conniption fits, or, when switched off, back tyres permanently fighting for grip.

The fix, as Audi discovered with quattro almost 40 years ago, is to send power to both axles and all four contact patches. Great for traction, terrible for getting your drift on out of corners - and that’s a trait BMW holds quite dear.

So, for this M5 BMW’s offering both. In its default setting the new super saloon is an all-wheel driven monster, ready to dig its claws into tarmac and launch from 0-100km/h in a claimed 3.4 seconds.

But then fiddle around in the drive menus and it’s possible to engage 2WD Mode for pure tyre shredding, smoke billowing, hooliganism.

In typical stiff upper lip German fashion BMW says the system allows the new M5 to be “compatible with historic values”, meaning that like every M car before it, it can take a bend with some degree of oversteer. True to an extent.

But consider the power at hand, and that 2WD Mode is only available with DSC switched completely off, and it’s clear that this clever addition is a token feature built in for customers who want to be very naughty at times. Anyone for doughnuts?

I drove the M5 in both modes on public roads and around the Estoril race track, and my findings were as expected. 4WD Mode is faster, 2WD Mode is more fun. There is an earlier touch of understeer when pushed to the ragged limit in 4WD but the extra traction on corner exits more than makes up for it in lap times.

With the front axle disengaged the M5’s steering weight lightens up, and mid-corner pitch angles can be adjusted with handy application of throttle.

But it must be said that anyone willing to explore this 5 metre-long sedan’s tail-happiness MUST have the driver skill to back it up. A tad too much pedal input at the wrong time, and it snaps like a coiled cobra toward the nearest hedgerow.

Impressively, and even with all the extra gear underneath to make all-wheel drive happen, BMW has managed to shave around 60kg from the new model.

This is thanks to a standard carbonfibre roof (the first on an M5), a lightweight exhaust system and optional ceramic brakes which shed 23kg on their own.

Under the hood is an evolution of the previous M5’s 4.4-litre twin-turbo V8. Disappointing maybe, considering the rest of the car is new from the ground up, but BMW’s done well to give it a fresh characteristic.

New turbos, higher injection pressure and a clever exhaust header routing makes for sharper, less laggy response.

Plus it’s much more vocal this time around. Under full load there’s a distinct turbo whistle mixed with the huff of eight big lungs expelling gases through four tailpipes. Think hurricane Irma meets the Daytona 500.

This M5 ditches the old one’s seven-speed dual-clutch ‘DCT’ gearbox for a new eight-speed torque converter unit.

Shifts might not be quite as crisp as before when flat out, but the tradeoff is much smoother operation at slower speeds. Overall I’d say the new transmission is an improvement.

Inside it’s all current 5 Series with digital climate control screens, various perfume spritzer settings, gesture controlled infotainment menus and leather trimmed dash inserts.

But there are some new M5 specific bits such as the gear lever with shift harshness settings built into its top, beautiful bucket seats with light-up logos under the headrests, a black alcantara headliner and a shiny red starter button.

Those M1 and M2 pre-programmed drive mode buttons M car customers know well from past steering wheels are now bright red toggles just ahead of the shift paddles, that look like something Maverick would have pushed before firing a heat-seeker at enemy Migs in Top Gun. A slightly tacky inclusion in an otherwise strictly business cabin.

The new M5 is due for South African launch next March, and though we don’t have pricing yet BMW SA says it’s aiming for right around the R1.8-million mark.

That’ll put it into direct price competition with its arch nemesis, Merc’s recently-introduced E63 S AMG - a car which beat the Bavarians to the so-called switchable “drift mode” mode punch, and with quite a bit more power at 450kW and 850Nm.

But for the record both cars come with the same claimed 3.4 second acceleration times and that’s probably down to the M5’s lightness. At 1855kg it’s exactly 100kg lighter than the Merc.

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