Here's how to celebrate Mini’s 50th birthday in style! Following the MINI CoupÃ© Concept, parent firm BMW is surprising visitors to the Frankfurt Motor Show with a bonus unveil – a stunning Roadster version. Designed to mark the brand’s half-century, the two-seater Roadster Concept takes MINI further into new territory. And it gives drivers in the market for the Audi TT Roadster, BMW Z4 or Mazda MX-5 another highly desirable model to consider. As with the low-slung Speedster variant we revealed in Issue 1,060, the drop-top is a real head-turner. It takes MINI’s instantly recognisable design and makes it sportier. Plus, like the CoupÃ©, it’s even more focused and fun-to-drive – but with an open roof. The front end shares much with the Cooper S, such as its bold headlights and chrome grille. Below those lies a wider, more aggressive splitter, while the A-pillars are steeply raked to give a more aerodynamic look. A low roofline, high waist and oversized wheelarches help create the impression of a chunky yet athletic machine. With the hood in place, it doesn’t have the controversial ‘floating’ roof shape of the CoupÃ©, but it certainly stands out, thanks to its ‘notchback’ profile, rakish rear screen and curved side window. Further neat details include the flat rear deck and a sporty lower spoiler, whih houses centrally mounted twin exhausts. Sporty stripes on the bonnet and bootlid, plus low side skirts and large alloys, complete the look. There’s no metal hood – instead, the covering is made of fabric, and it’s manually operated. This is a much lighter solution to a fully electric mechanism. Much like an MX-5’s hood, it is folded simply and neatly behind the occupants’ heads. The arrangement makes the Roadster surprisingly practical. Regardless of whether the roof is raised or lowered, there are 250 litres of luggage space. And, thanks to a clever lockable compartment linking the cabin to the boot, it’s possible to reach quickly into the rear storage area from inside the car, rather than have to get out and open the boot. The cabin benefits from heavily bolstered sports seats finished in soft leather. And safety is a priority throughout, so the Roadster Concept features a protective roll-over bar. In the event of a collision, this pops up behind the occupants’ heads in only 150 milliseconds. The A-pillars are stronger than on the CoupÃ© Concept, as are the sills and chassis floor. Under the bonnet lies the same engine as in the Cooper S – a 175bhp 1.6-litre turbocharged four-cylinder petrol unit. It produces 240Nm of torque, but can generate 260Nm for short periods during overboost. While official performance figures have yet to be released, we expect the Roadster to cover 0-62mph in seven seconds and accelerate on to 140mph. As well as being fast, the Roadster is frugal. It uses BMW’s EfficientDynamics package to give an anticipated 45mpg combined economy, plus low emissions. A clever dash-mounted display called NatureGuard reveals how efficiently the car is being driven. There are also gearshift and gravity indicators, the latter showing cornering force. There’s no on-sale date yet, but the Roadster could be in showrooms in 2011.