While BMW ->ke178 is busy revealing the first details on the upcoming 4 Series Convertible, our spy photographers were busy taking some photos of the upcoming 4 Series Gran Coupe. And we are not talking about an ordinary 4 Series Gran Coupe, but one painted in a very cool Estoril Blue and featuring the M Sport package.

As you can see the prototype wears little camouflage and mainly in the parts that are going to be updated by the M Sport Package. Basically the 4 Series Gran Coupe will be similar to the series 4 Series Coupe, with a slightly longer roofline and the extra pair of doors.

Internally known as the F36, the 4 Series Gran Coupe will borrow pretty much everything from its coupe brother, including the exterior design language, the engines and transmissions.

The new 4 Series Gran Coupe is expected to be unveiled in 2014 with production starting after the summer.

Click past the jump to read more about the BMW 4 Series GranCoupe.

Spy shots

On the exterior the 4 Series Gran Coupe will look identical to the coupe version, from which it will get the double-kidney grille, twin circular headlights and the large air intake in the front apron. However, the M Sport Package will make it look a little bit more aggressive.

This package will add a new M Sport front apron with larger air intakes and a new bumper with integrated diffuser. For the side the package will add new side skirts and of course a new set of 18-inch light-alloy wheels in M design.