BMW has finally sorted out the M4, even in the hedonistic and yet still ballistic Competition Convertible. New from the ground up, and now with all‑wheel drive, the 3 Series‑based high‑performance four‑seater sun‑seeker raises the bar for its mix of speed, handling, ride, comfort and control, blitzing all before it, even when you lower the taut fabric roof. It wears the M badge honourably.