June 23, 2014 9:45 AM | By Justin Couture, MSN Autos

2015 BMW M3 and M4 first drive

2015 BMW M3 and M4 (© Photo: BMW, Chris Tedesco)
  • 2015 BMW M3 and M4 (© Photo: BMW, Chris Tedesco)
  • 2015 BMW M4 (© Photo: BMW)
  • 2015 BMW M4 (© Photo: BMW)
  • 2015 BMW M4 (© Photo: BMW)
  • 2015 BMW M4 (© Photo: BMW)
  • 2015 BMW M3 (© Photo: BMW, Chris Tedesco)
  • 2015 BMW M3 (© Photo: Justin Couture)
  • 2015 BMW M3 (© Photo: Justin Couture)
Photo: BMW, Chris TedescoShow Thumbnails
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2015 BMW M3 and M4

M for Emotion

2015 BMW M3 (© Photo: Chris Tedesco, BMW)

Elkhart Lake, Wisc. – “Emotion,” says Albert Biermann, V-P of Engineering at BMW’s M Division, “was put at the forefront of development for the M3 and M4.” It’s unusual to hear this kind of talk from an engineer; emotion, is, unlike pounds-feet of torque or grams of weight, hard to quantify. But it’s the sort of benchmark that BMW needs to convince discerning and skeptical drivers that aren’t satisfied by just any performance product.

The “M” in “M Division” stands for Motorsport, but it may well stand for More, especially when you consider that 2015’s most anticipated performance cars offers more power, more torque, more acceleration and more speed, and also more efficiency, more comfort, and crucially, more technology. Is more emotion a possibility? We shall see, Herr Biermann, we shall see.

Action hero

2015 BMW M4 (© Photo: Justin Couture)

Kohler, Wisconsin, may be the most German-sounding and looking town in America. And though the nearest stretch of Autobahn is still a trans-Atlantic flight away, Kohler is just a stone’s throw from one of the most challenging race tracks on the continent: Road America.

In the pit lane, the M3 four-door and its two-door sibling, the M4, look race-track ready. Natural progressions from the muscled-up E90-generation M3s, they look every bit the potent track machine with hyper-steroidal fenders and a hood bulge that’s the mechanical equivalent of washboard abs. Garden variety 3 and 4 Series cars share a similar platform, but have dimensional differences including the track -- the all-important width between the tires. For the M3 and M4, this has been eliminated, giving them an identical stance. The M3 gains a carbon-fibre roof for the first time, while the M4 ditches the standard trunk lid for one made from a material scientists brew of carbon fibre and plastic composites. BMW engineers even integrated a rear spoiler into its design.

These are only two of the many changes BMW made to ensure the cars’ weight reflected their chiseled physiques. Invisible are a one-piece carbon-fibre drive shaft (-5 kg), a new six-speed manual transmission (-12 kg), an aluminum hood (-7 kg), and a lightweight aluminum axle carrier (-2 kg). Even the engine’s cylinder liners have been nixed, replaced by spray-on iron (-2 kg), and a lightweight crank shaft (-5 kg) installed to reduce engine weight. As such, for the first time, the M3 is lighter than the car it replaces. All that whittling away has paid off, with the car tipping the scales at 1,600 kilos – about 80 kilos lighter than before. True progress.

Bavarian Motor Works

2015 BMW M3 (© Photo: Justin Couture)

Up for debate, however, is the engine. No two generations of M3 have had the same engine, and the car has seen everything from a small four-cylinder, to two different straight sixes, to a V8 powering it. But the M3 and M4 enter a new era – the twin-turbocharged era. Power is up modestly by 11 hp to 425, but the gain in torque is 10 times that with more than 400 lb.-ft. on tap. Small turbochargers fed by carefully plumbed ducting allow the all-new three-litre to redline at 7,600 rpm – “damn high for a turbocharged engine,” Biermann boasts. And yet all of that torque is available from just 1,800 rpm.

With less weight to move and more grunt available, the new M4 can teleport itself to 100 km/h in 4.1 seconds when fitted with the optional ($3,900) seven-speed dual-clutch ‘box. That’s faster than any non-turbo Porsche 911 bar the anorexic GT3, and faster than its bigger brother, the M6, a car that stickers for nearly $50k more. As a side note, it’s also 15 per cent lighter on 91 octane too, which never hurts.

But for Herr Biermann, emotion comes not from the heart, but from the bones. Giant plates of aluminum were fitted to the Coupe and Sedan’s skeleton, while giant carbon fibre braces criss-cross the engine bay, attaching not to the strut towers but to the A-pillars through the firewalls, a technique perfected in the third and fourth-gen M3 race cars. The rear axle is bolted directly onto the car’s frame, foregoing bushings that mute road feedback. Bending rigidity is near as makes no difference to 40,000 Nm/degree – that’s just shy of BMW’s race cars, and it does so without a tubular roll cage. Why the effort? Biermann makes it clear: the stiffer the car, the more positive the feel, and the more the car is able to talk to you. Feel? Talk? This is language that the non-mathematically inclined (ie yours truly) can understand.

(Continued): The moment of proof
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