Porsche has revealed the first official pictures of the new 911 Cabriolet, ahead of its upcoming world premiere.It shares the same aluminium-steel body as the new Coupe (which we drove here), and features a brand new folding roof mechanism that contains magnesium in the frame to help keep the weight down. Porsche tells us this lightweight fabric roof makes the new Cabriolet \"significantly\" lighter than its 1,500kg predecessor. More details will be revealed at its premiere, but don\'t forget Porsche has managed to make the new Coupe 45kg lighter than before.Otherwise it\'s the same story as the Coupe. It gets a 100mm longer wheelbase, a wider front track, Porsche\'s new electro-mechanical power steering and the choice of a 350bhp 3.4-litre or a 400bhp 3.8-litre flat-sixer, both mated to that new seven-speed manual gearbox.No performance figures have been released just yet, but you can expect them to be a mere fraction slower than the Coupe. That car, fitted with the PDK gearbox, hits 0-62mph in 4.6 seconds (Carrera) and 4.3 seconds (Carrera S). Both Cabriolet models are said to return over 28mpg.Prices for the 350bhp Carrera Cabriolet start from £79,947, and £89,740 for the Carrera S Cabriolet. Both go on sale on March 3, 2012.