It had jaws on the floor at its unveiling in early 2006 and anyone who saw it at the various motor shows that year agreed that it must be built. The concept Rapide\'s design has barely been changed for the production model but there were monumental engineering hurdles that had to be overcome in order to preserve those achingly gorgeous lines. The full glass roof didn\'t make it into production but the rear quarters, while still snug, are certainly more accommodating than the show car. Inexplicably, though, sales are slow. Audi R8 Frankfurt\'s motor show-goers in 2003 weren\'t expecting Audi to come up with a two-seater supercar but the Le Mans quattro concept showed the company was on seriously good form, spurred on by three successive wins at the Le Mans endurance race. One of three different concepts unveiled that year, Audi chose this one for series production and named it the R8 after the Le Mans winning car, with the resulting model being almost indistinguishable from the show car in both looks and the technology underneath. Nissan GT-R The first concept was shown in 2001 and, four years later, the second was wheeled out at the Tokyo show. But the production version was still another two years off and, when it finally did arrive, it was obvious why Nissan took its time: the GT-R was epic. Overall, the styling changed little and that\'s good because it positively oozes machismo. It had the performance to back up its looks and showed the world that you could have 911 Turbo performance for half the money. Already a legend, its successor will be here in 2013. Bugatti Galibier It isn\'t in production yet but the Galibier is what concept cars are supposed to be about. Unveiled two years ago to Veyron customers and selected press for important feedback, the general consensus was that it was worthy of the name. And anyway, how would they top the Veyron for superlatives? The production Galibier is likely to be with us two years from now, physically similar to the concept with an interior that defies belief and clever detailing like the bonnet that\'s centrally hinged. With Veyron power, too. Peugeot RCZ The 308 RCZ concept unveiled at Frankfurt in 2007 shocked everyone. How could a car this gorgeous and futuristic be a Peugeot? And how could the French ignore the praise heaped upon its cute little head? They didn\'t and a production RCZ came along after a hurried two-year gestation. There was incredible pressure for it to look exactly the same so the design team gave us what we all wanted. The only compromise seems to have been the central dual exhaust but that\'s hardly a deal breaker. We need more cars like the RCZ.