Four-door coupes aren't exactly the hot new thing these days, but for BMW fans, the niche is getting ready to get interesting: the BMW Gran Coupe is being built, and these spy shots show it's not far from being ready.

Expected to join the BMW range as part of the 6-Series lineup, the Gran Coupe is the four-door counterpart to the standard 6-Series Coupe. With more room and similar performance, it could be an enticing buy for those that desire a little more practicality but can't give up the coupe-like look.

Based very closely on the concept car of the same name, the 6-Series Gran Coupe is expected to get the same powertrain options as its coupe and convertible siblings, which includes standard rear-wheel drive, optional rear-wheel drive (on some models) and a pair of engines, one V-8 and one six-cylinder. The V-8 is a twin-turbocharged 4.0-liter unit rated at 407 horsepower, while the six is the now-familiar N55 twin-scoll/single-turbo inline six-cylidner rated at 320 horsepower. Accordingly, it will also likely share 650i and 640i badging with the rest of the 6-Series line.

The Gran Coupe is expected to enter production sometime next year, likely for sale as a 2013 model. It will compete against the Audi A7, Mercedes-Benz CLS, and the rest of sport/luxury four-door coupe class.