Based on the recently revealed 4-Series Coupe Concept, these two renders show a possible look for the M4 Coupe and 4-Series Gran Coupe.
Artist known as Wildspeed (care of BimmerPost) envisions the new M4 with a 1M/M6-inspired front bumper seen on the M3 (F80) prototypes spied earlier this year. It also gets M sides skirts, wider fenders and a massive hood bulge as noticed in spy shots. Just like on the M6 Coupe, the new M4 could feature a shaped carbon fiber roof and double slatted grille with the "M4" badge.
As for the 4-Series Gran Coupe, this will probably borrow the head/tail lights of the regular 4-Series Coupe. It will also get the same engine lineup as the 3- and 4-Series models and will be priced just like the 6-Series Gran Coupe is positioned in the 5- and 6-Series family.
Check out the source links below for additional renders.