Prototypes for Maserati’s next model, a new coupe-cabrio based on the same platform as the Ferrari California, were first seen testing more than a year ago but soon disappeared once engineers started focusing on completing the car with the Prancing Horse badge. New spy photos reveal the Maserati version is back in testing, though from outward appearances it still has considerable work ahead of it.

The current Maserati Quattroporte has been on sale for nearly five years and has managed to tally more than 15,000 sales worldwide in that time. Despite the lack of significant upgrades since its introduction, the model continues to be a driving force for the company’s sales and was a key factor in helping the marque return to profitability last year after 17 years of losses. In order to keep sales strong as Maserati works on a full replacement due in 2011, the current Quattroporte saloon will receive a minor facelift and several mechanical upgrades.

The Maserati Quattroporte defined the modern comeback of the company, and has been praised for its looks and design the world over. Improving on such a stunningly beautiful and well-designed car is therefore quite a challenge, but Italian coachbuilder Carrozeria Touring feels it is up to the task with its estate version of the car, which it calls the Maserati Quattroporte Bellagio Fastback.

Just yesterday Maserati released the new Quattroporte Sport GT-S for Australia, and now we have an advance look at the 2010 GranTurismo Convertible.

Capping a rise in sales of 77 percent over the first quarter of 2008, Maserati is introducing its flagship Quattroporte variant, the Sport GT-S, to Australian roads.