This time the prototype has the retractable top down, with test drivers enjoying a sunny day near the Nürburgring.
Just as with the M3 and M4 Coupe, power comes from a 425bhp 3.0-litre six-cylinder in-line engine with M TwinPower Turbo technology with 550Nm of torque.
New six-speed manual gearbox with new throttle blipping function is standard, having lost 12kg compared to its predecessor. 7-speed M DCT will be optional.
The Coupe accelerates from 0-62mph in 4.3 seconds with the manual and 4.1 seconds with the optional 7-speed M DCT. The Convertible is expected to be a bit slower, due to a more complex and heavier roof system.
The M4 Convertible is expected to debut later this month at the New York Auto Show.