With both car manufacturing and new-vehicle sales in Britain well and truly in the doldrums, showrooms are badly in need of a little sunshine.

And if a little becomes a lot this spring and summer, then one sector of the market is sure to shine – cabriolets.

For, as sure as a harsh winter drives up sales of 4x4s, an outstanding summer will boost demand for drop-tops of all shapes and sizes.

If very warm weather is on the way – impossible to predict right now as Britain struggles to shake off the gloom – then 2009 could be the Year of the Cabriolet.

Which will leave one manufacturer, Fiat, sitting pretty with the soft-top version of its highly popular, retro-styled 500 due here this spring.

Called the 500C, a global preview of the chic convertible will take place early next month, March, at the Geneva Motor Show, Switzerland, with its Europe-wide launch to follow soon after.

And the sooner the better, for the new, British-built Mini Convertible launches on March 28, the car that is seen as the Fiat’s main rival.

The Mini model comes in Cooper form, with a starter price tag of £15,995. The Fiat starter version should retail at some £6,000 or so less than that.

Like the car, Fiat’s cabriolet pays homage to the open-top 1957 model, and it gets a powered soft roof that slides fully to the rear of the 500 when opened.

The appeal of using such an innovative sliding soft top means that the vehicle’s construction remains strong and safe, and that it retains the original 500′s dimensions – 3.55 metres long, 1.65 metres wide, and 1.49 metres high.

The roof material is available in three colours, ivory, red, and black, with a choice of several body colours, two of them unique to the new car – a brilliant Pearl Red and a Warm Grey.

Fiat fans will also be pleased to learn that it will share the same three powerplants seen in the existing 500, a 1.3-litre, 75bhp turbo-diesel, and 1.2-litre and 1.4-litre petrol engines.

As part of Fiat’s commitment to the environment and sustainable mobility, the new 500C incorporates a recently-announced Start&Stop system, which shuts the engine down in jams or at traffic lights, quickly firing it up again when the clutch is depressed for gear selection.

The 500C will be built at Fiat’s Tichy plant in Poland, and full pricing and specification are expected to be announced at the Geneva Show.

Anyone yearning for a sportier 500 will welcome news of the just-on-sale Abarth version, which is powered by a 1.4-litre, turbocharged petrol engine available in 135 and 160bhp outputs.

Performance figures for the 135bhp version are put at 7.9 seconds for the 0 to 62mph sprint and top speed 128mph – and this one is selling for £13,600.