2015 BMW M3 Sedan

BMW's all-new M3 Sedan is dynamically nearly identical to its two-door M4 Coupe sibling: a stopwatch reveals that both are sub-four-second cars to 60 miles per hour, a racetrack proves that the mechanical twins are equally as adept on a road course and a full afternoon of driving on public roads demonstrates that each possesses talented everyday adaptability.

Yet after driving both BMW models back-to-back over two full days in Portugal, it's clear there are a few noticeable differences, both objective and subjective, that don't require instrument testing to reveal. All it takes is a few hours behind the wheel of both cars to conclude that one is slightly more agile, and the other a bit more twitchy. One has better outward visibility, while its counterpart is unquestionably more convenient.

It is the little things – subtleties attained through seat-of-the-pants observations – that eventually allow me to choose a favorite.

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With the turbocharger pumping 18 psi over atmospheric pressure into the intake, the M3 develops 425 hp and 406 lb-ft of torque.

After only offering a coupe with the first-generation E30 M3, BMW launched a range of second-generation M3 models on the new E36 platform that included a coupe, convertible and sedan. When it rolled into showrooms in 1997, the 240-horsepower four-door was one of the quickest and best-handling sedans on the planet, leaving the Audi S4 and Mercedes-Benz C43 AMG in its wake.

Fast forward nearly two decades to the arrival of the fifth-generation F80 M3 Sedan, launched alongside its mechanically identical M4 Coupe and upcoming M4 Convertible siblings. Despite name and bodystyle differences, all three have been engineered to be the best in their class – no small feat, considering the imposing competition – meaning the new M3 Sedan is a formidable challenger.

While the standard F30 models in the States offer the choice between a turbocharged 2.0-liter four (N20), a turbocharged 3.0-liter six (N55) and a 2.0-liter four-cylinder turbodiesel (N47), the M3 arrives with a beastly, all-new, twin-turbocharged 3.0-liter inline-six fresh out of the automaker's M division. Wearing a new S55B30 engine designation, the all-aluminum mill is chock full of race-bred goodness, including Valvetronic variable valve timing, a forged crankshaft and a lightweight magnesium oil pan beneath its track-ready lubrication system. At full throttle, with the turbocharger pumping 18 psi over atmospheric pressure into the intake, the S55 develops 425 horsepower at 5,500 rpm and 406 pound-feet of torque starting at just 1,850 rpm – those numbers best the previous generation's eight-cylinder output by 11 horsepower and 111 pound-feet of torque with a reduced appetite for premium unleaded. Now, who still misses that V8?

2015 BMW M3 Sedan

By my calculations you could field a respectable enthusiast model for a bit more than $70,000.

Differentiating it from the standard 3 Series models, the exterior of the M3 wears new bodywork, including a new front fascia, flared quarter panels (front and rear), a new rear valance and a unique hood with a subtle power bulge – the hood and doors are made from aluminum, to save weight. Overhead, the exterior of the roof is offered in lightweight carbon fiber that helps lower the center of gravity, a first for the M3 Sedan.

The interior has been treated to the typical M suite of upgrades, including a wondrously thick three-spoke steering wheel, M instrument cluster, M sport bucket seats (driver and front passenger), M dead pedal and the M transmission shifter. While it sounds like there is an abundance of "M" smeared throughout the interior of the cabin, all of upgrades are tastefully integrated and do a great job of increasing its sporty demeanor. That said, I must profess that the near-white leather of my test car is a bit unmanageable, especially considering that it is a four-door (insinuating it could serve some family duty), but it appears classy with the contrasting stitching and carbon-fiber trim.

Those choosing the M3 Sedan over the M4 Coupe will be able to take advantage of the very useable rear bench, which seats three. Passengers aren't offered storage behind the front seats, which have hard backs, but they are provided an HVAC outlet with adjustable air flow and temperature and a 12-volt lighter socket. Both rear seats split and fold (60/40) to increase the utility value, and there are cargo nets and metal tie-downs in the trunk. When shutting, the lid's hinges disappear into the compartment's walls, meaning your prized carbon-fiber Specialized racing bike won't get crushed as you close the decklid.

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BMW says the M3 hits 60 in 3.9 seconds. I'd consider that conservative.

A vehicle configured like my test model will start with a base price of $62,925 (including $925 for destination) when it arrives in the States, undercutting the M4 Coupe by $2,200 and making it BMW's least expensive M offering. But, as is often the case, BMW brought a handful of identically prepared models to the launch in Portugal, and each was very heavily optioned.

The long list started with the stunning Yas Marina Blue Metallic paint ($550) and Silverstone Full Merino leather ($3,600). Added to that was the Driver Assistance Plus package ($1,900), Executive package ($4,300), Lighting package ($1,900), 19-inch black light-alloy wheels ($1,200), M Carbon Ceramic brakes ($8,150), M Double-clutch transmission ($2,900), Adaptive M Suspension ($1,000), Harmon-Kardon audio ($875), Parking Assistant ($500) and Enhanced USB plus Smartphone integration ($500). The miscellaneous equipment drove the as-tested price to $89,350. Before choking on the sticker price and crossing it off your wish list, know that by my calculations you could field a respectable enthusiast model for a bit more than $70,000. Without question, the test car was ridiculously optioned.

Punching the start/stop button immediately brings the direct-injected engine to life, where it quickly settles to a buttery smooth, yet entirely undistinguished, idle. As with the M4 Coupe, the M3 Sedan driver is faced with a smorgasbord of choices before driving off. All told, there are three different modes for the steering, engine and Dynamic Stability Control (DSC), and another three modes with the optional M-DCT. The default configuration is generally the least aggressive, but those wishing for a more engaging driving experience will want to press a few buttons to engage Sport or Sport+ modes. After rolling through the choices, I programmed the steering wheel-mounted M preset buttons to my favorites, which were Sport, Sport+, Comfort and MDM (M Dynamic Mode), respectively.

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I never once cursed the automatic, but I frequently wished I was driving a manual.

The standard 335i sedan is no slouch, sprinting to 60 mph in about five seconds flat when optioned with the eight-speed automatic transmission, yet the M3 with the seven-speed dual clutch gearbox takes it to a whole new level. The twin-turbocharged S55 spools up quicker than the single-turbo N55, and despite a 40-pound weight penalty (beefy high-performance components add mass), the M car reaches the same benchmark about 1.2 seconds quicker – BMW says 3.9 seconds, but I'd consider that conservative. Both cars are electronically limited to 155 miles per hour, but the automaker will offer an M package that raises the M3's maximum to 174 mph.

All of those figures seem entirely believable, especially in real-world driving. Slam the gas pedal to its stops and the sedan launches off the line with minimal turbo lag. The rear-wheel-drive M3 does an impressive job putting the power to the pavement, thanks to a sizeable contact patch (staggered Michelin Pilot Super Sports, sized 255/35ZR19 and 275/35ZR19) and the effective M Diff – an electronically controlled multi-plate limited-slip differential – managing the grip.

A traditional six-speed manual, a modified version of the gearbox in the discontinued 1 Series M Coupe, is standard. However, BMW says that 80 percent will pony up for the optional seven-speed M double-clutch transmission (M-DCT). The transmission snaps off each of its gears automatically, with the console mounted shifter or via the steering wheel-mounted paddles. It is difficult to fault the DCT's operation, as its operation is smooth and completely free of clunking, rattling or other mechanical oddities. Over two days of driving, on and off track, I never once cursed it for putting me in the incorrect gear, but I confess to frequently wishing that I was driving a manual. I'd forgo the DCT and spend the same money on the Adaptive Suspension and Lighting package.

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The M-tuned four-door carves the canyons with the agility and sureness of an Olympic slalom skier.

Few cars are as easy to drive quickly as the M3 Sedan. BMW consistently builds vehicles that are very well-rounded – acceleration, braking and cornering are all within the same circular performance envelope. A driver behind the wheel quickly gains confidence, as there are few surprises. Driving quickly, with the DSC in M Dynamic Mode, the M-tuned four-door carves the canyons with the agility and sureness of an Olympic slalom skier, never seeming to put a tread block on an incorrect patch of pavement. Cornering grip is impressive, especially on gravel-strewn public roads, and the carbon-ceramic brakes are easy to modulate. I ran most of the canyons in Comfort mode, as the other settings were too firm.

Kudos to BMW for renting Portugal's famed Autódromo Internacional do Algarve racetrack, known more simply as the Portimão circuit, for an afternoon of testing. On the impeccably smooth circuit, the M3 attacked corners at much higher velocities, yet held the same poise as on the public roads. Tossing the M3 into a corner is child's play, as the sedan settles quickly, turns-in well and then blasts its way out. Never once is there a feeling of being in a vehicle that is too large for this type of enthusiast play – I can't say the same about the M5, which weighs nearly 800 pounds more.

The vehicle's soundtrack deserves a mention. I'm not a huge fan of BMW's latest synthesized engine tunes that are piped into the cabin through the audio system speakers. The M3, like the M4, M5 and i8, are all faking it – the proper sounds are there, in all the right places, but it is being mostly created by the vehicle's Digital Motor Electronics and supplemented by the actual intake and exhaust. The notes are pitch perfect, sounding more like a V8 than an inline-six, and your mind is easily brainwashed by the trickery, but it's not real. Thankfully, bystanders outside the M3 are only able to hear a genuine combustion soundtrack, courtesy of the M signature quad pipes hung below the rear valance.

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BMW says the M3 Sedan and M4 Coupe share identical underpinnings... but they do drive differently.

I am indifferent – not frustrated, but also not convinced – about the electric steering. The upgraded Variable M Sport rack is very accurate, but the steering effort feels artificially weighted in each of its settings (especially on Sport+). The uncharacteristic feedback through the wheel does not affect handling, but it is a bit off-putting initially. But, truth be told, the steering annoyed me less the more time I spent behind the wheel.

BMW specifically stated that the M3 Sedan and M4 Coupe share identical underpinnings, including independent suspension with upgraded M-specific aluminum arms, chassis braces and a carbon-fiber U-shaped strut brace under the hood. The springs and struts are identical, as are the kinematics and tuning of each, but they do drive differently.

By the tape, each share the same 110.7-inch wheelbase, 183.9-inch overall length and front and rear overhang, but the M3 Sedan's body rides slightly higher on its suspension and its cabin is taller, meaning its overall height is about two inches taller than that of the M4 Coupe (54.4 inches vs. 56.3 inches). Each have the same track, but the body of the M4 is also marginally wider (0.3 inches). The M3 tips the scales at 3,595 pounds, which is a mere 10 pounds more than the M4 – less than the weight of two gallons of premium fuel – yet both carry their weight virtually identically (weight distribution is about 52 percent front and 48 percent rear on both).

2015 BMW M3 Sedan

BMW's objective is to level the playing field, then ask the buyer if they want a coupe or need a sedan.

Driving each back-to-back, I eventually notice several differences. At speed, the M3 seems to break its rear tires free earlier than the M4, feeling slightly less planted under high-G situations. And, during aggressive maneuvering, the M3 feels less agile – its mass shifts a bit slower than the coupe. Both of these handling differences are likely attributed to a slightly taller center of gravity. But even as I note the slight variances in dynamics, I remain convinced that only an expert will be able to find any dissimilarities in their lap times.

And that appears to have been BMW's objective from the start; to level the playing field in terms of powertrain, suspension and equipment, and then ask the buyer if they want a coupe, or need a sedan. Taking into account the extra convenience, additional passenger capacity and its improved appearance – I'd argue that the sedan's taller greenhouse is better proportioned to the platform – please toss me the keys to an M3 Sedan.