A closer look at the 2015 BMW M3 sedan and M4 coupe: Turbocharged performance is gonna cost you

By the time the 2015 BMW M3 sedan and M4 coupe were revealed at the Detroit auto show, we already knew a lot about what to expect from the Roundel's newest generation of high-performance driving machines. It was no secret, for example, that the new M3 sedan and its two-door counterpart, the M4, will be down two cylinders and a few hundred pounds from their predecessors.

Now that we've had a chance to get a look at the cars in production trim, here's a closer look at what's under all the aggressively vented fascias, spoilers and M badges.

Despite losing a liter of displacement, the new twin-turbocharged 3.0-liter inline-six is more powerful than the naturally aspirated 4.0-liter V8 it replaces. Thanks to BMW's M TwinPower Turbo forced-induction system, which uses two low-inertia turbochargers to produce a max 20.15 psi of boost pressure, the engine's output is 452 hp (between 5,500 and 7,300 rpm) and 406 lb-ft of torque (between 1,850 and 5,500 rpm). Compare that to the 414 hp and 295 lb-ft produced by the V8.

On paper, this upcoming powerplant should be better than the old engine in every way. It even weighs less -- around 22 pounds less, in fact. Cars equipped with BMW's dual-clutch tranny will do 0-60 mph in 3.9 seconds; six-speed manual-equipped cars do the same in 4.1 seconds. Yet we found that the new turbocharged engines lacked some of the V8's soul when we tested preproduction prototypes. Much of that had to do with a muddled engine note; at the time, BMW engineers assured us that a fix was in the works.

Power is one thing, but keeping weight down in an era when the current 3-series is bigger than a mid-1990s 5-series is another. The pair of Ms is larger than the cars they replace in every dimension: The M3 gets 3.6 inches longer, 2.8 inches wider and 0.9 inch higher, while the M4 gets 2.2 inches longer and 2.6 inches wider (it is actually 1.7 inches lower than the M3 coupe).

Fortunately, the new Ms shed pounds thanks to lightweight (and naturally, costly) materials like carbon fiber and aluminum. BMW says the M4 will weigh 3,300 pounds while the M3 weighs 3,351 pounds.

You're probably wondering how much this is all going to cost you. BMW hasn't released an exhaustive breakdown yet, but Bimmerfest has an early look at pricing figures. Once you factor in the standard $925 destination fee (which, as Bimmerfest notes, is subject to change), you arrive at a hefty $62,950 for the M3 sedan and $65,125 for the M4 coupe. A big jump over the outgoing models, yes, but you pay big bucks for more power and less weight these days.

Will it all be worth it? We'll let you know after some time behind the wheel.

The North American International Auto Show, known to most as the Detroit auto show, continues to serve as a barometer for the entire industry. This year, we'll expect to see the new Chevrolet Corvette Z06, the 2015 Ford Mustang and the BMW M3 and M4. The 2014 Detroit auto show is held at Cobo Hall in Detroit, MI and is open to the public from January 18-26.

By Graham Kozak