A prototype of the BMW M4 Cabrio was spied almost undisguised while conducting some last-minute testing ahead of a very possible 2014 reveal.

A prototype of the BMW M4 Cabrio was spied almost undisguised while conducting some last-minute testing ahead of a very possible 2014 reveal.

This is our best look yet at the convertible M4 which as seen in previous spy photos will feature a foldable hardtop. Joining the already launched M3 Sedan and M4 Coupe, the latest M cabrio closely mirrors its fixed roof sibling with an aggressive body kit, muscular wheel arches, sculpted hood and a quad exhaust.

Power will come from the same six-cylinder 3.0-liter TwinPower Turbo gasoline engine outputting 431 HP (317 kW) and 406 lb-ft (550 Nm) of torque. The engine will work with a standard six-speed manual or an optional seven-speed DCT. The manual Coupe does 0-62 mph (0-100 km/h) in 4.3 seconds and 4.1s with the DCT while the Convertible will probably be 0.1 - 0.2s slower due to a slightly higher curb weight.

Top speed is going to be limited at 155 mph (250 km/h) but those who will opt for the M Driver's Package will be able to raise the speedometer's needle to 174 mph (280 km/h).

A public debut could occur as early as next month at the Geneva Motor Show.

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