If your Lamborghini Gallardo Spyder is becoming a bit tedious you could switch allegiance north of the Alps to Bugatti’s new Grand Sports. Bugatti has confirmed it will build 150 of the new Veyron Grand Sports after the open-top version of the world's fastest car was launched at the Pebble Beach Concours. Why the world needs an open topped car capable of 407km/h remains unclear.Plastic see-through roofKudos to Bugatti engineers for preserving the Veyron’s superlative performance despite what must have been a nightmarish redesign project to accommodate the removable transparent polycarbonate (read plastic) targa roof. There is an emergency canvas soft-top for the absent minded in case of emergencies; performance is limited to 130km/h with it in place though.Like the Veyron 16.4 coupe, the Grand Sport tops out at 407km/h - if you have your own runway. With the targa roof removed it’s limited to 360km/h if you can deal with the epic wind buffeting. For high-speed open top runs a helmet is recommended.Key design changes from the coupe are the taller windscreen to reduce cabin wind intrusion, with substantial reinforcement to the Veyron's inner structure to compensate for the structural loss of the open roof. The last technical detail raises a question as to why there is an open topped version at all. McLaren hardly diluted their technological achievement with an F1 convertible back in the late 1990s did they? Safety features strongly in the open-topped redesign too. Sills and transmission tunnel have all been beefed up, while the B-pillars are braced with a new carbon fibre strut. The carbon fibre doors have been strengthened with a side impact bar. For roll-over protection, the Veyron coupe’s distinctive air intakes are re-designed to include 100mm wide carbon-fibre tubes to protect occupants. Clever.Huge performancePerformance, despite being nearly 100kg heavier than the coupe at 1 968kg, is still epic. Beyond the 407km/h top speed, acceleration is cartoonish with 0-100km/h in 2.7 seconds and 0-300km/h in 16.7 seconds. Those keen on posing around the Camps Bay beachfront can look forward to the 41.6l/100km urban cycle average consumption. The Grand Sports will cost a cool £1.14 million before taxes - around £150k more than a Veyron, and of course each time you stop you’ll have to answer a flood of inquiries regarding why you didn’t buy the coupe instead.The Grand Sport will take total Veyron production up to 450 cars by 2011, breaking the company's earlier commitment to build no more than 300 Veyrons. It’s called marketing and profiteering taking precedence over engineering. The first 50 cars will only be available to current Veyron owners.