Unveiled at the 2012 Geneva Motor Show, the Lamborghini Aventador J Roadster is the topless version of the already insane Aventador. Just when you thought Lamborghini had just developed one of their best looking (and performing) cars, they came up with this one. And it is simply stunning. The roofless and windowless concept car uses the same V12 engine as the Aventador and develops 700HP which is transmitted to the wheels via its seven speed automated transmission. The car has also been stripped of its air conditioning and radio units to save further weight. Cost? 2.8 Million dollars. The video below is sure to get your heart racing.