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.