Bugatti has shared a teaser to its social media, including the Facebook post you see below. The teaser, posted on December 19, speaks of "An automotive solitaire that never hit production." From the look of things, Bugatti will unveil this mystery car on December 21 at 10:00 CET. Bugatti also tagged auction house RM Sotheby's in the post, indicating this car will be up for auction.

What the car actually is remains slightly muddy. Clearly, this is a Bugatti Chiron of some variety (though there are many varieties of the Chiron). Bugatti uses the word "profilee" in its hashtag, a French word meaning "profile" in English.

However, profilee has another meaning. The word can also be used to describe a person who was or is being profiled. Or, in this case, a car. Of course, this could be very literal. The provided photo is shot in profile. More likely, it's a hint at what this car represents.

Our first possible theory is that Bugatti is selling its development mule. The final Chiron, a one-of-three vehicle called the L'Ebe, has been delivered, making the car officially sold out. The company has no real need to keep it, and some brands have had their development cars make it into public hands. Most notably, a Ferrari LaFerrari mule was sold by RM Sotheby's earlier this year.

This may also be a "last one, we promise" move from Bugatti. Sure, Chiron production has ended. But the brand has one floating around, or at least so we say. Someone's order was canceled, a deposit bounced, et cetera, et cetera. The brand probably has one laying around, likely produced before the Chiron L'Ebe mentioned above so as to keep with the L'Ebe being the last one.

If this is the case, it will surely command a serious amount of money at auction because, to Bugatti's ultra-wealthy customers, money is not real. We're sure whatever the car is will be very fast, very special, and of course, very pretty. We'll find out in just a few days.