Mini will unveil the Mini John Cooper Works Convertible at next month's Geneva motor show.
The Mini is powered by a 208bhp 1.6-litre turbocharged petrol engine that shoots the car from 0-62mph in 6.9 seconds and returns 39.8mpg with CO2 emissions of 169g/km.
The Convertible is only marginally slower than the John Cooper Works hatchback, which gets from 0-62mph in 6.5 seconds.
The engine is a lighter and stronger version of the unit found in the standard Cooper S model, and has a larger air intake and modified exhaust system to enhance its performance.
The car also features Electronic Differential Lock Control, which slows the inside wheel if traction is lost while accelerating out of bends, giving the Mini faster cornering and a sportier drive.
Other additional standard kit over the Cooper S includes enhanced brakes, an Alcantara steering wheel, 17-inch alloy wheels, sports seats and JCW embossed kit, including the gearstick and floor mats.
The Mini John Cooper Works Convertible goes on sale next month, with prices starting from 23,470.