The Lamborghini Aventador J is one of the most extreme speed demons ever built--and not surprisingly, it sold quickly.

The roofless, V12-powered supercar fetched about $2.8 million, or about 2.1 million euros at current exchange rates, Lamborghini CEO Stephan Winkelmann said on Tuesday at the Geneva motor show. That doesn't include value-added taxes, he said.

A Lamborghini spokesperson declined to reveal the identity of the buyer.

The Aventador J summons the spirit of the 1970 Jota, a one-off version of the Miura. Like that car, the Aventador J is also a one-off, though it does offer an idea of the appearance of potential a roadster version of the Aventador.

The Aventador J packs 691 hp from the same 6.5-liter engine as its fixed-roof, serially produced sibling and is clad in a shade called Rosso Red. It makes extensive use of carbon fiber, including a patented material called "carbon skin" for the interior. The car is so extreme that the driver must wear a helmet, though the car can be registered for road use, Lamborghini says.

Meanwhile, the Aventador is off to a brisk sales pace, Winkelmann said. The supercar has an order-bank list of 18 months, and its launch in the second half of 2011 helped propel Lamborghini to sales of about 1,600 cars last year around the world, an increase of 23 percent.

Additionally, Winkelmann hinted that another vehicle, expected to be an SUV, would join the Gallardo and the Aventador in the Lambo lineup.

"We might have in the future a third model," he teased in Geneva.

Stay tuned.

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