After releasing the broad-stroke tech specs of the 2014 BMW M3 Sedan and 2014 BMW M4 Coupe last week, Bimmer has now released the nitty-gritty tech details of the rip-roaring duo.
While these agonizingly exacting design details make the well-sculpted twosome of mid-size German road warriors into ‘ultimate driving machines,’ repeating the particulars verbatim could very well put you to a coma, as they are from the minds of humorless, dark grey-clad M division engineers. Named things like Fritz, Helmut, and Leopold, these men have few passions in the world outside numbers, efficiency, and bland cheeses.
These dour men design brilliant cars, yes. Should you find yourself next to one of these Bavarian bores at a dinner party, however, I suspect you’d likely rather give yourself a prison tattoo with a rusty hypodermic needle than spend more than a minute discussing the intricacies of a launch control ECU.
Accordingly, we’ll take a look into the details, but I’ll try my darndest to make them a bit more palatable – to spice them up a bit.
Engine
Although an inline four-cylinder powered the first-gen M3, BMW upgraded to inline six-cylinders for the second- and third-gen M3s. Then BMW broke the mold a bit and bolted a V8 to the fourth-gen. While this choice added some much-needed power to the breed, it also represented a messy divorce from the inline six powerplant that many had seen as quintessential BMW.
Now, however, it’s back. BMW has reverted back to the much-loved six, but this time included twin turbos. The new turbo six produces 430 horsepower and 369 pound-feet of torque. This represents a 16-hp and 74-lb-ft power increase over the outgoing V8. Intriguingly, Bimmer brags the new six also achieves 25 percent better fuel economy than the last motor.
How did Fritz and the gang squeeze more power while also producing fewer carbons? German magics.
More specifically, it’s the combination of mono-scroll turbochargers, direct fuel injection, VALVETRONIC variable valve timing, and double-VANOS variable camshaft timing that give the sixer all its shake.
Don’t start yawning yet. Instead, think about it this way: Sure, I could explain to you that those bits are operated by a strange mix of oil pressure and electronics. Should you turn around and try to explain those systems to anyone outside the confines of a BMW Club meeting, though, you’d immediately become a social pariah. Suffice it to say, when those bits break, you will want to have sold your M4 already.
Just a bit down from the valves and turbos, in the bottom of the engine, engineers designed a closed-deck crankcase, which increases rigidity and allows cylinder pressure to be increased for maximized power output. And instead of liners, the M3 and M4 cylinders feature a twin-wire arc-sprayed coating, which represents a significant reduction in engine weight. What ‘twin-wire arc-sprayed coating’ is exactly, I don’t know. I think it’s metal from the heart of a primordial volcano, though.
Bodywork
BMW has not released the full production photos of the new M3 Sedan and M4 Coupe. It has, however, detailed some of the aerodynamic curves of the forthcoming cars.
What we do know from BMW is that the M engineering team worked very hard to create bodywork that would be not only utilitarian but also compelling to look at. More importantly, though, the body was penned to create downforce while also providing ample cooling to the engine, turbochargers, and brakes. Here’s the tricky bit, though: the body must also be very slippery in the wind. In this way, BMW says it’s succeeded.
Appropriately, the designers added a Gurney spoiler lip at the rear of the M3 Sedan and an integrated spoiler lip at the rear of the BMW M4 Coupe. The wings and lips reduce lift by an equal degree at both the front and rear axle and also make the cars handle more responsively.
The M engineers also created M gills with integrated air breathers that minimize turbulence in the front wheel arches and intricately sculpted side-view mirrors. Unlike the wing and lip that are designed to keep the Ms pushed firmly into the tarmac, the gills reduce wind resistance, allowing the M3 and M4 to go more quickly in the corners and straights.
From my standpoint, BMW M3 coupes and sedans have never been the best looking things. In true Germanic utilitarian fashion, the body designs serve a purpose, but rarely inspire. I fear that same underwhelming motif will continue into the M3 Sedan and M4 Coupe. My worries aside, though, Bimmer’s description of the body lines makes it’s clear some intricate sculpting went into the curves and shapes of the new mid-size Ms.
Transmissions, driveshaft, and differential
Many industry analysts prophesied the fifth-gen M3 Sedan and first-ever M4 Coupe would be offered sans manual transmission. While, given the recent move by BMW’s rivals to axe manual transmissions from high-end models, this projection made sense; it was, however, hasty.
No, the Bimmer boys still have a manual available for the mid-size M twins. In fact, the gearbox is more compact, lighter weight, and quieter than before. Weighing 12 kilograms less than the manual bolted to the outgoing V8, the new manual gearbox uses an innovative new carbon-friction lining in its gear synchronizer rings. And carbon, as we know, is always better because it is A.) more expensive and B.) lighter weight.
Finally matching other high-performance cars, the new M manual transmission will blip the throttle on downshifts, which is a feature previously reserved for the M Double Clutch Transmission. So now you’ll be able to shift with the best of them – without having any real skill! Frankly, that’s the idea of the Ms anyhow. So we won’t complain too loudly.
Speaking of driving skillfully without any real skill, this brings us nicely to the seven-speed M Double Clutch Transmission. BMW even admits this transmission is designed to combine “the apparently conflicting values of absolute sports performance and comfort.”
How does it do that? With two simple features: one more speed than the manual so that the gear ratios can be closer together and – most importantly – a launch control, which takes all the skill in a full-tilt 0-60+ mph sprint.
Regardless of which transmission you specify, both will route power to the rear differential through a carbon driveshaft, which is not only lighter but also more rigid, allowing it to more efficiently transfer power to the rear-end.
That rear-end, unlike the outgoing M3, is electronically controlled. Called the Active M Differential, the unit uses an electric actuator to constantly vary the degree of wheel engagement. Depending on which setting the driver chooses, the electronic diff can squelch oversteer and understeer or allow for greater wheel slip – i.e. make the thing all drifty.
Steering
Lastly, we come to the bit that we’re least pleased with. OK, it’s the only bit we’re displeased with, really: the electronic power steering.
It’s no secret Germans believe they know best. It’s also no secret they have little regard for American automotive tastes. This is why as a group they insist on bolting up numb electric power steering. They think it’s better than hydraulic.
Although BMW brags the new system “offers the gifts of direct steering feeling and precise feedback,” we won’t hold our breath. You see, although the M3 Sedan and M4 Coupe electric steering includes an integrated Servotronic unit that electronically adjusts the level of steering assistance according to the car’s speed, we doubt very much it’ll be able to match the vivid feedback of a hydraulic system.
That’s because the Germans don’t like twitchy steering like we Americans do. Germans want numb, heavy steering. They find feedback wholly uncouth. So while your M4 will likely go exactly where you point it, you won’t really know what’s going on where the rubber meets the road.
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