It has that air of touch-me-and-I’ll-drill-you-a-third-eye-socket about it, the M6. Now parked at the bus stop, it chinks and ticks with heat and in the morning sun I’m thinking, well… I’ve been a bit hasty here. We’d best nail it down one of Europe’s best driving routes, known only as the Ronda road, and then drift it to oblivion at a private race track before making this particular decision. Fully prepared to suffer the burden of this imminent process, the keys are taken, the V10 is stoked and those waiting for the number 341 bus are left with the unmistakable smell of Pirelli P-Zero Corsa.
At Fives and Sixes
So what’s the main difference between an M5 and an M6? Couple of doors, carbonfibre roof, a pinch of wheelbase and a topping of rear track. Same engine, same gearbox, same many things, but when all’s said and oversteered, they’re quite different bits of kit. That is an important distinction to be heeded by anyone still thinking that Five versus Six is only a question of practicality.
The M boys have tried hard with this car. It is no longer possible to go what Porsche has always called the RS route with a series production car, and that was never the aim of this project. They had to find a method of reducing weight, not compromising on safety or equipment and, crucially, improving every aspect of the driving dynamics: making it feel like a coupé should feel.
Study the detail and it’s clear that BMW’s M-division very quickly ran out of obvious weight-saving options. The usual method of binning sound-deadening materials, the odd airbag, rear seats and every electric seat motor in sight was not available. So they went to extraordinary lengths to gain what is officially just a 45kg advantage over the M5. Actually it’s 50kg.
There are two aspects to effective weight saving. First, and most obvious, is the process of simply trimming away the kilos to make your horsepower more effective and your chassis more responsive. The second is rarely mentioned outside of motorsport, but is fundamental to the M6’s design brief. If BMW M was unable to drastically reduce the mass, then it would redistribute some of what had to remain. Centre of gravity is the Holy Grail of chassis engineering, and the M6’s is 60mm lower than an M5’s. That’s a lot.
Most obvious of these alterations is the carbonfibre roof. First seen on the limited-run M3 CSL, this is the first time it’s been used on a full production car. If the net saving of 4.5kg over a steel roof panel doesn’t strike you as anything special, the fact that this weight has been shaved from the very top of the car is more significant than the overall saving. The roof is bonded in place, and all the work is carried out on the main production line.
Then there are the slinky alloy wheels, the spokes of which barely look strong enough to prop up a supermini, let alone this 1710kg lump. Made of forged aluminium, they shave a full 1.8kg of unsprung mass from another critical area. After this, the attention to weight-carving detail is reduced to infinitessimal levels. The front and rear bumper supports are made of carbonfibre, saving 20 and 40 per cent respectively over conventional aluminium items. The rear windscreen is a little thinner than that of a standard 645.
But however much BMW M wants us to think that its dietary plan has played the biggest role in shaping the M6, it’s actually the tyres (admittedly working in conjunction with the reduced mass and lower centre of gravity) that are the strongest indication of how serious a performance tool the M6 is. The Pirelli P-Zero Corsa system has only been used on two production cars before this: the Ferrari 360 Challenge Stradale and the Porsche 996 GT3 RS. It is a soft compound ‘cup’ tyre that offers much more performance than a regular road tyre, and the results are staggering.
And if you were asked to define the main difference between Five and Six in one word? Sharpness. Everything the saloon does, the coupé executes a touch faster, more athletically, with the benefit of reduced inertia and heightened responses. In isolation the differences aren’t that marked. I can’t, for example, tell you that the steering of the M6 feels any different to that on the saloons – they’re both excellent for accuracy and offer poor feel. Nor can I say that the coupé rolls less than the saloon, but it does scoot through curves significantly faster and feel more… planted.
Unsurprisingly, this is straight-line weapon like little else. Shorn of a few kilos and with an identical 500bhp at 7750rpm and 384lb ft of torque at a high 6100rpm as the M5, it’s a car that feels immensely fast on the wide, cascading surroundings of the Ronda road.
All of the praise heaped on the M5 can be levelled at this car: there’s just the right amount of torque to make rapid progress a simple, untaxing procedure, but still a considerable incentive to run the V10 to the 8500rpm limiter. That’s worth doing if only to revel in the noise and watch the head-up-display speedo crank through the digits with a vigour that would seem familiar to Michael Knight, but only when he’d hit KITT’s ‘turbo boost’ button.
I’m sure the M6 will shave the thick end of a second off the M5’s scorching 9.8sec 0-100mph, partly on power-to-weight ratio, but mostly because it’s now possible to use almost full throttle in first gear and everything in second. Those Pirelli tyres even make a difference in a straight line. The 155mph speed limiter, where allowed, takes regular beatings, and even though BMW isn’t willing to talk theoretical maximums, it does make a cheeky reference in the press pack advising those interested in such matters that the 330km/h (205mph) speedometer should give you a clue. De-limiting M6s will become a lucrative business over the next few years.
The seven-speed SMG ’box is carried over unchanged: full-bore shifts make you want to pray forgiveness for the health of the rear diff, but it’s an effective transmission. The other carry-over from the M5 is the MTM function that harmonises damper stiffness, DSC stability control function and gearshift speed, and that will provide hours of fun, or confusion, depending on your level of technophobia.
Composure is an M6 watchword. Even with the electronic dampers set to soft (there are three settings) it’ll only brush the suspension stops over large compressions at speeds that would land you a lengthy stay at Her Majesty’s pleasure in the UK. It remains supple though, with an ideal damping action, never taking more than a single compression and rebound action to smooth the surface away. It’s not what you’d call a very comfortable car – the tyres have stiffer sidewalls and construction than normal – but as a pay-off for such grip, it strikes a good balance. If only the miserly 70-litre fuel tank was larger.
Full attack on the track
At the track, I’m beginning to be sure about the M6. Even three years ago it would have been inconceivable to lap a circuit like the Ascari race resort without peeling the shoulders off the tyres and crucifying the brakes. But this is a car that will lap the Nordschleife in close to eight minutes and is rarely happier than lapping into the sunset. M-division boss Gerhard Richter is quick to rebuff any talk of the 348mm ventilated and cross-drilled discs not being up to the task. But they do begin to drone after a couple of hard 100mph stops and the pedal lengthens. They never give up entirely, but then they don’t offer the type of unquestionable, unfading strength I’d expected. You ask yourself if Porsche would have signed off these rotors, and have to say no.
Surprise number two at the track is the amount of understeer, given the special rubber. But this isn’t front-push of the howling, tread-shredding variety, it’s a deliberate set-up decision, and means that you can easily drive around it. First, by loading the car up more progressively: this way the front end does push on initially, but then it stabilises and the car becomes more neutral. And the other is demonstrated in the photographs. Pirelli’s vulcanisation gurus have nothing to combat 500bhp at maximum yelp. This car was made to drift, and the M variable differential is carried over unchanged from the M5.
And now, hot laps slithered, I’m sure about the way the M6 drives. I like the concept: the two-plus-two stunted adults packaging. The on-road composure mated to genuine eight-minute Nürburgring lap time. But with a list price of €105,000, there’s every chance it could have an £80,000 sticker in UK showrooms when it arrives sometime around September. That’s strong, and undeniable though the appeal and added dynamicism over the of the M6 are, they don’t amount to £15,000-worth over the M5.
But I suspect that might be missing the point of this car. It’s fast, so damn fast, gives new meaning to any notion of street presence and is a worthy addition to the M stable. Perhaps rather than answer the M5/M6 question, we should chuckle that BMW even sees fit to offer us such a choice. Me? I just love saloon cars.