Nice shape, a bit too upright in the nose for a coupe. it should be more like the 6er and slope back from the centre of the grill
If the image shown is based on the 1er platform and correct proportions, a 6 could be shoehorned in
The design's front is very upright in the nose (grills) like the F20/F21. (suggests they still need the engine bay length for a 6)
My guess is it will either have the 125i/328i's powerplant and outputs and the 135i as the go fast or they will morf the front to slope more and run with the 125i/328i's powerplant and outputs and could go for that persistantly rumoured 'M' 4 pot engine as the M car.
This render is out there for the feedback it will generate.