Just when we were starting to grasp BMW->ke178’s recent name change and switch-up of its bread-n-butter 3 Series->ke290 sedan and the new-for-2014 4 Series->ke3834 coupe, the German automaker threw another curve ball: the 2015 4 Series Grand Coupe. So now the coupe version of the 3 Series sedan has its own four-door sibling. Makes perfect sense...

The news here is the future addition of the M4 Grand Coupe -- the spiced-up version of BMW’s not-a-3-Series four-door sports car. BMW has yet to release any official images of the M4 Grand Coupe, but our rendering wizard has sent us this amazing preview of the upcoming super sedan. The actual M4 GC is set to debut at the Geneva Auto Show in early March 2014. Until then, this is what we’re going off of.

In all reality, the 4 Series GC is a different car than the 3 Series sedan. It’s fully based on the regular two-door 4 Series. It even shares its same wheelbase and overall length as the 4 Series coupe. Its major difference is in the B-pillars on the back. A higher roofline, shorter front doors, and the addition of two rear passenger doors makes the 4 Series GC a much more usable, yet still coupe-like five passenger saloon.

We’re suspecting the M4 GC will get the same M treatment the M3 got, which is a 3.0-liter TwinPower turbocharged in-line six-cylinder, making a stout 425 horsepower and 406 pound-feet of torque. The six-speed manual gearbox and the optional seven-speed, double-clutch transmission will likely be offered in the M4 as well.

Click past the jump to read more about the 2015 BMW M4 Gran Coupe.

TopSpeed Artist's Rendering of the 2015 BMW M4 Grand Coupe

Exterior

The exterior of the M4 Grand Coupe is both distinctly 4 Series yet undeniably M-ed up. The large, gaping front grille with its purposeful and lines give it the sportiness expected from a M product, while the more coupe-like rear roof section reminds you of its 4 Series Grand Coupe background. The combination is beautiful.

The rear hatch of the 4 Series Grand Coupe is still present in its M form. It's amazing how the designers and engineers have hidden its hatchback functionality in its coupe-like structure. The casual passer-by would never know what lurked under the rear deck lid.

Interior

The interior will likely get the same M treatment the 3 Series gets. The carbon-fiber dash insert, the tri-spoke steering wheel and the infotainment system to name a few. Details, like the M-designed door sills, dead pedal, gearshift lever, leather steering wheel with chrome trim and circular instruments with white graphics, give an upscale and sportier appearance to the M3 and won't be out of place in the M4 GC.

The seats will feature strong bolstering to keep occupants snugly in place. Power operation and heating elements will likely still be available for those looking for the touches of comfort. Four adults are able to ride without issue, although there are better sedans available for long distance travels as the suspension will be much more firm than in the standard 4 Series GC.

The 4 Series GC will share its same hatchback design with its M version, providing a level of functionality not usually found in track cars. The rear hatch opens much like a hatchback, lifting both the deck lid and rear glass to reveal a large cargo hold. The 40/20/40 rear seats fold for an even greater cargo area.

Drivetrain

The M4 Grand Coupe will be powered by BMW's sweet 3.0-liter, in-line six-cylinder boosted by two mono-scroll turbochargers. High precision direct fuel injection, fully variable valve timing, and variable camshaft control helps squeeze every last ounce of power from the lightweight engine.

If power outputs remain the same as in the M3, the 3.0-liter will produce an impressive 425 horsepower between 5,500 and 7,300 rpm while a tire-shredding 406 pound-feet of torque comes in at 1,850 rpm and stays strong through 5,500 rpm. What's more, the M TwinPower Turbo engine boasts a lower weight than the outgoing 4.0-liter, V-8 found in the previous M3 while netting a 25 percent increase in fuel economy.

Transmission will likely be the same as well, and in the M3, two transmission options are available: a standard six-speed manual transmission and a seven-speed M Double Clutch transmission. Both transmissions have electronic features that make any driver look like a professional driver. The six-speed has an automatic throttle-blip system, much like that of the 2014 Corvette C7’s Rev Match system, that gooses the throttle within the split seconds between gears during a downshift, increasing smoothness of shifts.

Laying down the power is BMW Active M Differential. it uses an electronically controlled, multi-plate, limited-slip setup designed to send power to the tarmac most effectively. Its takes into account the throttle position, rotational speed of the wheels, steering angle, and the car’s yaw rate – all coming from the Dynamic Stability Control system. This sort of smart technology helps mediocre drivers feel like Randy Pobst.

Since the M4 Grand Coupe doesn't officially exits yet, we don't have solid numbers on curb weight or 0-to-60 times. But the current M3 equipped with the M-DCT hits 60 mph in just 3.9 seconds and 4.1 seconds with the six-speed-equipped model. We expect those times to grow by a tenth or so with the possible addition of Grand Coupe weight.

Prices

Pricing at this point is pure speculation. Since the base 4 Series Grand Coupe has yet to exist, much less its more powerful M version, it's really an educated guess. But that won't stop us.

The 4 Series two-door coupe that is currently on sale starts at $40,500. Looking at the $3,000 premium the 6 Series Grand Coupe requires over the standard two-door 6 Series, a $3,000 price hike wouldn't be too far fetched in the 4 Series' case. Then comes pricing for all the M goodies. The current crop of M-badged cars and SUVs command anywhere from $30,000 to $40,000 on top of the base model. If that stays true with the M4 Grand Coupe, you'd be looking at a starting price between $73,500 and $83,500.

Competition

2014 Mercedes CLS 63 AMG 4MATIC

The Mercedes->ke187 CLS 63 AMG has normally been competition for BMW's 6 Series, but with the addition of the 4 Series, the CLS' competition grows. The big German car is powered by a 5.5-liter V-8 that delivers a huge 550 horsepower and 531 pound-feet of torque. Power is sent through an AMG SPEEDSHIFT MCT seven-speed sports transmission and then to all four wheels through AMG's 4MATIC all-wheel-drive system.

Zero to 60 mph comes in a blistering 3.7 seconds and top speed is limited to 155 mph. Pricing for the CLS 63 AMG hasn't been announced yet as it's release date is in August 2014.

2014 Audi S6