2015 BMW M4 & M3 Details:

  • First-ever turbocharged M3 engine | New M4 model | Widebody styling
  • S55B30T0 3.0L i-6 biturbo engine | Single-scroll turbos | One-piece, carbon fiber driveshaft
  • 425hp, 406 lb-ft | 0-60mph in 3.9sec (M-DCT) | 3540 lb (6MT) - lighter than predecessor
  • 6-speed manual or 7-speed M-DCT | Improved economy | Priced from $62925

Electronics: M preset button | BMW Apps | Connected Drive | Augmented engine noise | Active suspension and diff

+ Pros: Awesome driver's car | Sedan practicality or Coupe looks | Improved economy and lightweight | Massive torque | Manual and composite brakes option | Sounds great

- Cons: Can't really think of any...

Entering its fifth generation, few cars carry the weight of expectation like a new BMW M3. Perhaps Porsche's engineers feel the same responsibility, but they're playing in more rarified air. The cost of a 911 means its developers have bigger margins, but a BMW must be practical, versatile and affordable. And for a new M3, it must also be damn fast: able to compete with the 911 on a racetrack.

Bimmerfest 2014 - Pasadena, CA

This year, we're also seeing the birth of a new vehicle, the BMW M4. It could potentially steal the M3's crown with the stylistic advantage of its sleek coupe body. However, Albert Biermann, head of development for BMW M explained that the team went to extraordinary lengths to ensure both cars were virtually identical mechanically and dynamically. "The M3 is an icon," he explained. "We couldn't have it upstaged by the BMW M4!"

So while the BMW 435i has several key advantages over the 335i, you'd be hard pressed to detect the differences once the "M" badge is applied. During two days of hard driving, which included a section of Portuguese road used by the World Rally Championship, and laps of the sublime Autodromo Internacional Algarve in Portimao, we didn't discern any major differences.

The engineers admit the BMW M4 is about 50 lb lighter (US regulations might show a different weight because they must account for popular optional extras) and had miniscule differences in setup - it's slightly lower, has a different weight distribution and center of gravity - but we're only talking about single percentage points.

Some drivers seemed to pick a favorite but the differences are more stylistic. Do you like your toys to have two doors or four? Do you prefer the F80 M3's fender flares, or the F82 M4's cleaner lines?

We're traditionalists. So we'd take the M3. We like the badge and the greater practicality, but concede we felt the M4 drove slightly better, although it's entirely subjective.

What we should be worrying about is how the cars drive. Do they deserve the pedigree the badge commands? To be honest, we were slightly concerned during our first spell behind the wheel...

2015 BMW M4 Convertible Announced

The two M presets on the steering wheel had been programmed by our hosts with different settings - M1 was more of a comfort program, while M2 was more racy. We were advised to start in M1 and explore some real roads.

On the freeway, the M3 and M4 are hooligans. Both tickle along at 100mph as if it were 55. Pull the paddle two, maybe three times, and you can unleash the sort of accelerative force usually preserved for supercars.

With 0-60mph conservatively quoted at 3.9sec using the M-DCT transmission (4.1sec for the 6MT), there's a surge of acceleration that barely retards in the higher gears. We nudged up to 145mph and found it as eager to continue as it was at 80mph.

Hard acceleration is accompanied by a deep, bassy bellow that initially puts you in mind of the outgoing 4.0L V8, although the new S55 engine only revs to 7600rpm - lower than the V8's 8400 but still high for a turbo-six.

While engine power is similar to the V8, what really differentiates the engines is the S55's abundance of torque. Where the V8 had 295 lb-ft at 3900rpm, the F8X has 406 lb-ft from 1850 to 5500rpm. So while the V8 had to be kept in its sweet-spot at high RPM, the S55 has a different character. You don't need to be as busy with the paddles, which should also suit the manual transmission. And while the M-DCT might be quicker to 60mph and easier to drive on-track, those of us who appreciate and desire greater control were delighted to learn you can still get a manual transmission, cementing the BMW M4 and M3's status as a true driver's car.

There were rumors that the F8X models might not get a manual, especially since most of its competitors have eradicated them. However, BMW expects 20% of its sales to be 6MT. Perversely, most of them will be sold in the US, the country that's otherwise helping to banish the stick-shift, but when it comes to our sports sedans, we still want a third pedal!

The gearbox was taken from the BMW 1M, which in turn came from the 135i. For this application it was modified internally for strength, gaining carbon-coated synchromesh. They also removed 26 lb, making it 66 lb lighter than the M-DCT.

When using the 6MT, the software provides rev-matching blips on down changes, unless the driver selects Sport Plus. At this point, it's up to him to execute heel-and-toe downshifts.

The original aim of the development team was to get the car under 3500 lb and they came impressively close. A manual transmission and carbon-ceramic brakes will get you to within a few pounds. If it wasn't for the latter's six-piston calipers and the fact it needs larger 19" wheels, they might have succeeded.

This is the first time a new M3 has been lighter than its predecessor, which is a big deal. Weight is the biggest enemy of acceleration, braking, handling and economy, so reversing the trend should pay dividends for owners.

Other weight-saving technologies include the electromechanical power steering, which saved 8 lb compared to the previous M3. Then there is the aluminum front subframe that's 9 lb lighter than on the 435i and gains extra bracing. The hood is 17.5 lb lighter than the E9X, the fenders saved 8 lb and the carbon-reinforced plastic trunk on the BMW M4 is 11 lb lighter than the 435i - the M3 retains its steel trunk but the M4 required the new part because the coupe is inherently less aerodynamic. As a result, it has a molded spoiler similar to the E46 M3 CSL. This equalized the downforce between the two cars, with the carbon lip on the M3's trunk more of a cosmetic addition than a high-speed requirement.

Although we don't have a figure, the S55B30T0 engine is lighter than the similar N55 3.0L in the 435i. In this application, the steel cylinder liners are replaced with an iron coating sprayed onto the bores. This is then machined to create a very thin friction layer that protects the pistons.

There's also a new crankshaft that's 30% stiffer than the N55 and 4.5 lb lighter. It will inevitably be one of many parts that 335i and 435i owners will eye jealously for their own cars...

The engine has been fitted with what BMW calls its third-generation turbochargers. Two single-scroll units were designed to work with the 7600rpm rev limit, forming part of the company's new high-revving turbo engine philosophy. They don't see why a turbo motor must have a narrow powerband, although getting turbos that are small enough to be lag-free, yet able to provide so much power up to the rev limit is quite an achievement.

The power supply should be consistent because a great deal of effort went into engine cooling. It uses a water-cooled intercooler and has five radiators behind the front bumper to control operating temperatures.

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