We first told you about a planned roadster version of Alfa Romeo’s upcoming 4C sports car in March of 2011. Since then, there hasn’t been much to report on the open-top sports car, although Fiat has done a good job of dropping the occasional teaser on the 4C coupe.

Now Autocar, citing sources close to the project, brings us the first real update on the 4C convertible that we’ve seen. Development is ongoing, and the topless 4C is expected to debut some 12 months after the 4C coupe hits Alfa Romeo dealers.

Power will come from the same 1.75-liter turbocharged four-cylinder engine as the 4C coupe, with output specified as simply “over 200 horsepower.” Alfa Romeo is projecting a curb weight of under 1,870 pounds for the coupe (although the roadster may be heavier due to chassis bracing), which should produce a 0-100 km/h (62 mph) time of under five seconds.

Early 4C development was handled by race car builder Dallara, although the project has progressed to the point where Alfa Romeo has taken complete ownership under the guidance of Fiat engineering head Mauro Pierallini. Like the coupe, the roadster will use a carbon fiber tub, aluminum subframes and composite body panels to save weight.

When the range-topping 4C debuts, it will likely resemble the concept car shown, but won’t be an exact copy. While the 4C roadster will sit atop Alfa Romeo’s product range, the upcoming Mazda-built Alfa Romeo Spider will give buyers a less expensive way to enjoy open-air motoring with an Italian flair.