Lamborghini Aventador J at the 2012 Geneva International Motor Show

• Looks like: a chop-top Aventador
• Defining characteristics: It’s missing a roof and windshield
• Ridiculous features: Almost everything is made of carbon fiber
• Chances of being mass-produced: Lamborghini will make and sell just one

A racing-inspired version of Lamborghini’s Aventador supercar was unveiled in Geneva today, but it’s missing a few things, namely a roof and windshield. Not quite a concept and not a typical production vehicle, the Aventador J is a one-of-a-kind convertible, and Lamborghini will build and sell only one unit.

The J in the name is borrowed from the FIA world motorsport organization’s Appendix J, which defines the technical specifications of racecars in each class, according to Lamborghini.

This “street-legal work of art,” as Lamborghini calls it, is based on the Aventador LP 700-4 coupe. It shares its platform and powertrain with it: a 700-horsepower, 6.5-liter 12-cylinder engine with a top speed of nearly 200 mph.

The Aventador J’s doors open upward. It rides on five-spoke aluminum wheels, with 20-inch rims at the front and 21-inchers at the rear. Its body is made largely of carbon fiber-reinforced polymers, with lots of carbon fiber trim inside and out, including seats with inserts made with a Lamborghini-patented blend of flexible carbon fiber fabric. Lamborghini calls it Carbonskin and says it’s “made of woven carbon fibers soaked with a very special epoxy resin that stabilizes the fiber structure and keeps the material soft.” Carbonskin lines the cockpit as well.

Aside from the windshield and roof, the car is also missing interior components like air conditioning, radio and the navigation system. According to Lamborghini, “these would simply detract from its one and only raison d’être as an extreme driving experience.” The lack of equipment keeps the Aventador J to a light 3,472 pounds.

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