new Lamborghini Aventador J unveiled

This is the Lamborghini Aventador J, a one off, road legal roadster that company boss Stephan Winkelmann says is a testament to his firm�s commitment to pushing the limits of design, despite increasingly rigid road car regulations.

As such, it takes its name from the world motorsport governing body�s �Appendix J� regulations, which define racing car class specifications. The J also invokes Lamborghini�s history, referencing the one off 1970 Lamborghini Jota, which was a high performance version of the legendary Miura.

The roofless roadster has taken centre stage on the firm�s Geneva motor show stand before being sold off at an undisclosed price as �the most extreme expression of Lamborghini DNA in existence�.

Lamborghini has pledged that no other prototypes or museum pieces will be made in the same vein � although insiders have confirmed that a more widely available but less extreme Aventador roadster will be launched later this year.

Modifications are restricted to the J�s extreme styling; it�s powered by the same 690bhp 6.5 litre V12 as that of the fixed head car. It also has the same four wheel drive system & uses a modified version of the same pushrod suspension.

The J is based on the Aventador�s carbonfibre monocoque, although it has been extensively modified to accommodate the roofless structure, as well as being stripped out in the interests of saving weight. The bodywork has also been substantially reworked to boost aerodynamic grip.

The loss of the roof, windscreen, air con, stereo system & sat nav mean the Aventador J is significantly lighter than the coup�; Lamborghini says the interior has been stripped out, as any gadgets would detract from the �raison d�etre of this car: to provide an extreme driving experience�. It also features upward opening doors that are substantially thinner & lighter than the coupe�s. Lamborghini has not released its weight, however.

At 4900mm in length, 2030mm wide & 1110mm high, it is 120mm longer & 26mm lower than the Aventador coup�; the width is the same, but Lamborghini says this is the lowest car it has ever built. Despite the absence of a windscreen, the height difference isn�t as great as you might expect due to the protruding rear view mirror, which sits on a periscope like arm, & the two rollover bars that sit behind the seats.

The front end is also narrower than that of the fixed head Aventador & features a dramatic air scoop with central fixing braces & upward tilting winglets on the outer edges. Lamborghini claims these, plus the substantial rear spoiler, have been designed to give the Aventador J the look of a Formula 1 racing car.