❝THE SUPER-SALOON IS AT THE POINT WHERE ONLY ALL-WHEEL DRIVE WILL DO❞
MATT SAUNDERS ON THE NEW BMW M5’S SWITCH TO TWO DRIVEN AXLES
The super-saloon has clearly reached that point. The one that cars at the upper end of the hot hatchback class hit several years ago: a power and performance threshold that can be passed only by switching from one driven axle to two.
In a formerly front-driven 1.5-tonne hot hatchback, it came at about 300bhp. For a rear-driven 1.9-tonne executive express, it’s come at twice that. But it has certainly come; the demise of the traditional rear-wheel-drive Mercedes-amg E-class (now a 604bhp car itself) suggested as much earlier this year, and now BMW M division’s decision to switch its 40-year-old performance icon, the M5, from ‘standard drive’ to all-wheel drive confirms it. Hot Audis have been that way all along. Alpina’s recently unveiled B5 is a four-wheeldriver – and any Svr-badged Jaguar XF is sure to be that way, too.
Time for new rules, then – at least at the very top of the ’bahnstormer saloon tree. Over the next few years, we’ll find out who will be able to execute the four-wheel-drive super-saloon the cleverest; who will best use the very latest drivetrain technology to broaden the versatility and reach of the breed without abandoning the handling purity and balance that has been a primary pillar of their appeal for so long.
The people at BMW’S M division plainly think it’ll be them. For M, four-wheel drive is a sales and marketing necessity. North America remains BMW M’s biggest market by some distance, and having a fourwheel-drive M saloon option could dramatically improve sales there, where customers are increasingly looking for performance cars they can continue to use during the winter months. But sales success will remain important on this side of the pond as well. Here, attitudes towards a switch to four-wheel drive among BMW M’s core European customers might not quite be so receptive.
And so, as if to prove how little there may be to fear from the development, BMW invited us to its Miramas proving ground, which stretches over a 2000-acre site in southern France, for an early test drive in the sixth-generation M5. The car hasn’t even been seen at a motor show yet and is still a while from final engineering sign-off before a sales debut in 2018. But such is BMW M’s apparent confidence in the car’s new ‘M xdrive’ drivetrain technology, and its canny awareness of the need to start winning people over early to the idea of a four-wheel-drive M5, that it provided a heavily disguised prototype, a few hours of track time and some obliging experts for us.
THE TECH ANGLE
Up on a car hoist in one corner of an immaculate Miramas workshop,
hovering just above head height, sits the new M5 and, beneath it, M division vice president of engineering Dirk Hacker is pointing and explaining.
He has covered the obvious bits already: the chain-driven clutch taking drive off to the front axle on demand; the rear differential, developed from the one on the M3 and M4, that has new carbonfibre clutch blades for more precise torque vectoring; the new eight-speed torque-converter gearbox (as light as the old seven-speed M-DCT, apparently); the new adaptive dampers (from ZF Sachs); the brakes (a choice of standard ‘compound’ iron discs with blue calipers or BMW M’s carbon-ceramic stoppers with gold calipers); and the wheels and tyres (19in with a choice of Yokohama or Continental rubber as standard, or optional 20s on Michelins or Pirellis with a slightly wider section on the rear axle than on the front).
Then Hacker points at a small metal box, about the size of two decks of playing cards, that’s housed immediately behind the offside front wheel on the left-hand-drive prototype we’re poring over. “This is the real breakthrough,” he says. “This is what we call the Central Intelligence Unit. A chassis brain, if you like. It can overrule the individual ECUS for the stability control, the four-wheel-drive system, the rear differential and the transmission to make sure every part of the car is working towards the same aim. This is the first time any M car has had a centralised controller with the power to control every sub-system governing lateral and longitudinal dynamics.”
The chassis brain is also the main reason why the new M5 can offer its driver so many driving modes and such unparalleled mastery over exactly where the car sends its torque. Start the car from cold and it’ll default to a four-wheel-drive mode that gently favours the rear axle with stability control on. Enter the Dynamic Stability Control (DSC) system’s M Dynamic mode and you get a little more torque at the rear axle, a little more yaw contribution from the locking rear diff and a bit less intervention from the stability control. So far, so familiar. But turn DSC off completely and the M5 offers a new sub-menu with a choice of three further drivetrain modes: 4WD, 4WD Sport and 2WD. In the first two, the driveline effectively takes over responsibility for stabilising the car during limit handling from the brake-based stability control system – the 4WD Sport mode apparently allowing plenty of slip angle and throttle steer, should you want it, before gently transferring a share of the drive forwards. In 2WD mode, all the torque is sent rearwards and then funnelled between the individual rear wheels to create as driftable an M5 as ever there was. Or so they say.
The M5 has individual settings, too, for steering, engine, suspension and gearbox shift speed – but unlike in the new Mercedes-amg E63 S, it isn’t bothered how you combine them with that 2WD mode. You can have a comfy-riding, easy-steering, auto-shifting armchair skid machine if you want to. And, frankly, I would.
It’s too early for performance stats. For now, all the engineers will say is that they are working towards a car with “more than 600 horsepower” (615 is quietly hinted at); “significantly more than the current car’s 516lb ft”; and 0-62mph in “less than 3.5sec”. The car would be about 65kg lighter than the last one, were it not for the addition of the four-wheel drive system, which makes the difference marginal.
Enough talk. Time to drive.
THE DRIFT ANGLE
We take to one of the proving ground’s dry handling circuits: a loop of
When I switch off the DSC, it goes from very good to excellent
In 4WD Sport mode the M5 is adjustable, entertaining, but precise
tarmac about the same length and width as the one we use to set handling lap times at the UK’S MIRA proving ground, with a mix of tight second-gear corners and quicker third and fourth-gear bends.
While I’m getting used to the control weights, the grip level and the performance available, there’s a moment to note that a reasonable amount of criticism hasn’t persuaded BMW M to drop its ‘exhaust noise modulation’ strategy for this car. The M5’s engine isn’t the most characterful V8, but as you dial up through ever sportier modes on the powertrain, you’ll notice it getting louder and slightly more synthesised sounding. That’s because the car is playing an imitation exhaust barp at you. Because it’s only synthesised noise, you don’t have put up with it when the car’s in Comfort mode. Even so, it remains an annoyance – and a disappointment, in my book. A proper M car should sound not only better, but also authentic with it.
But the M5’s performance level is quite something. It takes a couple of laps until I’m comfy enough to use full power, while the car’s grip and response levels are becoming apparent – but when it comes, the big car really flies. There’s the same slightly compliant, elastic feel to the power delivery as the previous, F10 generation M5 has: not a sudden, sledgehammer of torque such as is delivered by the new E63, but a more progressive build-up and the need to keep that motor spinning above 3500rpm to feel it at its best.
Now, which handling mode is the car in? I engaged M Dynamic mode on the stability control and Sport+ on the suspension and steering before we left the pit lane – but if you told me the car was already in one of its more agile, rear-drive-biased drivetrain settings, I wouldn’t argue. It’s turning in fast and neatly, with better steering feedback than the last M5 had and great stability. But it’s also finely balanced mid-corner, sticking to its line and staying neutral in its attitude as I accelerate away from the apex. This is the M5’s standard mode. I haven’t even got as far as switching off the DSC yet. But when I do, the handling poise, adjustability and involvement gradually progress from very good to excellent.
In 4WD mode, the drive system allows little or no power-on understeer if you drive competently enough. You can slide the car just beyond neutral and, if you’re smooth and slight with your corrections, it’ll keep the lion’s share of torque at the rear wheels.
The 4WD Sport mode lets you be more aggressive on turn-in and then hold a good quarter turn of corrective lock through the heart of a bend. Be any naughtier than that – or if the car changes direction more suddenly – and it’ll gradually feed enough drive forwards to help you gather things together neatly, rather than suddenly intervening and spoiling your fun.
After 4WD Sport, 2WD mode actually feels a bit slow and untidy. The handling is allowed to be more luridly sideways than the F10’s ever was and there’s no end of slip angle to be had anywhere you might be brave enough to dial it up. But, if anything, the relative shortage of traction available and a slight untidiness in the car’s close body control as the lateral load in the car switches, together with a faint tendency for the rear differential to vector torque away from the loaded wheel just a little bit too abruptly at big drift angles, make the M5 begin to feel a little bit rough and ready like this.
A 15min test on Miramas’s wet grip test track underlines the clear impression that the big M car is at its best in 4WD Sport: adjustable and entertaining but composed, precise, tractive and fast with it. The extra driven axle pours on the grip and stability smoothly and intelligently, but only after your level of control over the car’s position and attitude on the track has begun to deteriorate – like the best stability control system a super-saloon could ever have.
Is it possible that a four-wheeldrive M5 could handle even better than a rear-driven one? It’s very early days for pronouncements like that but, on this evidence, it seems we really can believe it.