The 'Number One' Gran Sport was pre-sold at last summer's Pebble Beach Auction for $3.19 million US, with part of the proceeds ($900,000 to be exact) being donated by Bugatti to the Pebble Beach Company Foundation Charity.
Billed as the fastest production convertible in the world, the Gran Sport retains the coupe's 1,001 HP quad-turbocharged 16-cylinder engine but comes with a removable lightweight transparent polycarbonate top as well as an emergency soft top that is stowed away in the trunk.
Other changes include the redesigned air intakes for the 16-cylinder mid-engine that feature 10-centimetre wide carbon-fibre elements to offer protection in the event of a roll, reinforced monocoque structure around the side skirts and the transmission tunnel plus stiffened B-pillars.
Bugatti also updated the car's interior with moisture-resistant, backstitched leather and added a range of new equipment features including a reversing camera with 2.7-inch monitor integrated in the rear-view-mirror, and the "Puccini" sound system with digital signal processor.
As for the Gran Sport's performance figures, with the roof closed it can reach a top speed of 253mph or 407 km/h. Open it up and you'll have to do with speeds of up to 224mph or 360 km/h (that's 11km/h or 7mph more than Bugatti initially projected). If you get caught up in a rain and are forced to use the emergency soft top, the supercar's top speed is restricted to 80mph or 130 km/h.