There will be a choice of either the 325bhp 3.6-litre flat-six engine or, in the Carrera S model, a 3.8-litre power unit developing 355bhp.
Both models have exactly the same top speed as their Coupé counterparts – 177 mph and 182 mph respectively.
The Coupé versions of the new 911 outperform the Cabriolet models by a few tenths of a second only in terms of their acceleration. The 3.6-litre version of the convertible Carrera (with manual gearbox) accelerates to 62mph in 5.2 seconds, the Carrera S Cabriolet manages it in 4.9 seconds.
The new convertibles will feature a choice of 18 inch or 19 inch alloy wheels, Porsche Stability Management and Porsche Communication Management, including a CD radio with nine loudspeakers, and a wind deflector.
The Porsche 911 Carrera Cabriolet will be priced at £65,260 and the 911 Carrera S Cabriolet at £72,230 and will be available in the UK from April 9.