BMW has earned a reputation for being one of the most socially in tune automakers out there. Time and time again, we've seen BMW->ke178 involve its fans in some way. Whether its through promos, Twitter contests, or even the occasional social marketing endeavor, the German automaker knows how to tap into its fans and get their feedback.

It certainly looks like BMW is going on that route again with the release of a teaser sketch of a future BMW model on its Facebook page. The company didn't release any specific details on what car this is, opting only to pose the question (in German): "Welcher BMW ist hier in einer frühen Design-Skizze zu sehen?"

Translated in English, the question means "Which BMW is seen here in an early design sketch?"

Obviously, speculation has run rampant on what model this is. Based on its looks, we're venturing a guess that this could be the upcoming 4-Series GranCoupe. The dimensions appear to be there, including the low roofline and the front fascia is similar to what the renderings, sketches, and spy shots of the 4-Series.

Hopefully, BMW provides us with the answer to its own question sooner than later.

Click past the jump to read more about the 4-Series

4-Series History

Information really started flowing about the 4 Series back in late-2011, when we caught a coupe that was slightly larger than a 3-Series but smaller than a 5-Series testing. With its super-heavy camouflage, it was easy to come to the conclusion that this was, in fact, the rumored 4 Series.

Not long after we caught the coupe model, we spotted the convertible variant out and about. We didn't learn too much from those spy shots with the exception that the 4-series was setting up to offer up a wide array of models.

Things became really interesting when we caught an M variant for the 4-Series testing. This inspired us to create a rendering of just how awesome this new performance coupe would look.

Then came the oddest of the bunch, the GranCoupe. This is an oddity because it is not what we traditionally classify as a coupe -- two doors -- as it is a four-door variant. Well, traditionally that would mean this should be a 3-Series, given its number of doors, but German automakers like to label sleek four-door models as coupes... Strange, huh?

The last progression in the 4-Series history was when BMW brought a concept model to the Detroit Auto Show in 2013. Unfortunately, little was revealed beyond the design language and its amazingly decked-out interior.