First images and details of the Geneva Motor Show-bound Fiat 500C have started to circulate the internet ahead of the official announcement of the new cabriolet version later this morning.

The Fiat 500 cabriolet, to be known as the 500C, is the first niche version to be drawn off the 500 platform since its launch on 4 July 2007. The 500 was built in a joint project with the new Ford Ka, and both cars are based on an adapted version of the Fiat Panda's underpinnings. Much as the Panda has seen a raft of niche versions built on the overall theme, the 500 will also receive the same treatment as it goes forward. A stretched 'Giardinera' version is in the planning pipeline, although the recent dramatic global slowdown in new car sales has seen Fiat, along with most of its rivals, taking the step of reviewing its entire future model development schedule.

In the 20 months since it arrived with a bang during a glittering extravaganza held in Turin, the 500 has proved to be a runaway sales success, and collected a host of important industry awards; these were topped off by the ultimate accolade of them all: Car of the Year 2008. As well as finding buyers across Europe, the 500 has gone on sale in countries scattered around the world such as Japan, Australia, New Zealand, Mexico, Brazil, Argentina, Thailand, India and South Africa. Within three weeks of the order book opening in July 2007, that entire year's production set at 58,000 was sold out, forcing Fiat to start ramping production immediately. Current production is running at around 200,000 units per year.

Now the first niche version, the 500C, is set to go on sale, a cute convertible that will arrive in the showrooms just in time to take advantage of the traditional pre-summer rush to buy convertible cars. And while the 500 a-year-and-a-half-ago unashamedly drew on the roots of its iconic predecessor, so does the new  500C which will feature a roll back canvas roof that will evoke memories of the original's model cabriolet versions half a century ago.

Fiat has created a unique canvas roof for the 500, retaining the B- and C-pillars and roof frame on three sides to reportedly keep structural chassis strength very close to that of the hatchback. It means that safety concerns that come with an open-topped car have been addressed. The compact electrically-operated sliding roof section will be built by Magna Car Tops at a site near the Tychy factory in Poland where the 500C will be assembled alongside its closed-roof sister. Much attention has been focused on developing highly compact roof hinges and sliders, and when the roof is stowed rear luggage space is only very slightly reduced. A glass window is fitted into the rear of the canvas to provide visibility above that usually found on a canvas roofed car. A number of colour options for the canvas roof, as well as the front wind deflector, will also be made available.

The same three engine configurations as the fixed-roof hatchback will be retained by the 500C: the entry-level 1.2 (70 bhp) gets the petrol range underway which is topped by the 1.4 (100 bhp) while a turbodiesel option is provided by the award-winning 1.3 Multijet (75bhp) as under the skin there are few changes made. The new fuel-saving Start&Stop technology will be offered on the options list. The current model's three basic trim levels: Pop, Lounge and Sport, will be carried over, as will the wide-ranging customisation programme which will be further extended to include options exclusive to the 500C.