Why is the new 3 coupe and M variant being called the 4 and M4?
Because BMW wants to.
Same goes for the chassis designation.
M3 Edition Grilles|Painted Reflectors|Matte Black Vinyl Window Trim|CF Performance Spoiler|35% Tint|19" Satin Black Avant Garde M359|Lux H8 V3
OEM Aero Lip|M3 Side Skirts|LCI Tails|M-tech Rear|Duke Dynamics CF Performance|Cyba 4.0 Black Chrome