This forced a package of alterations to be made that were both expensive and compromised the car's handling, ride, and gear shift.

With new management, new marketing initiatives, and continuing revisions to the car's engineering to answer public concerns, future vehicle plans, including the development of a four-seat model, had not been far advanced.

They soon realised that the powertrain of the City-Coupe was ideal for a small sports car, with a compact turbo engine driving the rear wheels via a 6-speed automated manual gearbox.

Following Smart's ‘reduce to the max’ philosophy and general innovative approach, a concept for a super compact, practical, and pure sports car was generated.

At the same time, a decision was made to develop Mauer's idea for a coupe version as a concept car for the Paris motor show a year later.

As the third design director of Smart during the Roadster's development, Sinkwitz had to bring the concept to production in a very short time.

Weighing as little as 790 kg (1,742 lb), the Roadster is intended to provide the emotion of driving a sports car at an affordable cost.

British motoring television show and magazine Top Gear praised the Roadster, awarding it Fun Car Of The Year for 2005.

In 2003, German tuning house Brabus created a prototype version of the Roadster Coupe with two merged 3-cylinder engines to celebrate the 100th anniversary of the Solituderennen.

This V6 bi-turbo powerplant had a maximum power of 160 kW (218 PS; 215 hp) for a weight of only 840 kg (1,852 lb), giving it the same power-to-weight ratio as a Porsche 911 Carrera 4S.

The bigger engine also forced a change from separate coil springs and dampers to concentric units to support the de Dion rear suspension.

In March 2006, Smart unveiled the final variant of the Roadster at the Geneva Motor Show: a limited collector's edition.

It was based on the top model Brabus Xclusive with 101 PS (74 kW; 100 hp) and came with a satin brown-metallic paint job.

Only 50 in the world were made and featured all the Brabus trimmings plus special black Alcantara and leather seats with red diamond pattern stitching.

These cars were finished in Ferrari Red with matching light surrounds and bumper sections, the Tridion safety cell being all silver.

In 2006, David James initiated Project Kimber, an attempt to restart production of the Smart Roadster in the United Kingdom.

These vehicles were retrofitted with an engine from a Suzuki GSX-R motorcycle to improve power and throttle response, which was accomplished with a kit made by a British company.