Cars need context, especially big, fast, expensive cars. Wisely, Lamborghini opted for Miami rather than Chipping Sodbury for the launch of the Aventador Roadster, supplying the context this car was so obviously custom-tooled for. Bathed in balmy sun despite being early February, this is a city that wears its underpants outside its trousers, asks you to embrace your inner freak, and is home to a ridiculously high number of beautiful people.Not entirely coincidentally, there's a tonne of money here too, which means a Monaco-style density of high-end automotive tackle and a populace that is more likely to whoop its appreciation than hurl abuse at you. I counted seven different Ferrari 458 Spiders, one Enzo, more Rolls-Royce Ghosts than you'd see in the factory car park, and had my eyeballs lacerated by an Aston Martin Rapide in matt black, with gold grille and gold 22in alloys. Inner freak duly embraced.No Lamborghini is for the faint of heart or shrunken of violet, but by lifting the lid on its Aventador Roadster, the other Italian supercar big gun may have created the most outrageously theatrical car of the lot. And the lid in question is extremely cool. OK, so it's not a folding hard-top in the mould of the 458 Spider or McLaren 12C Spider, and the owner has to imperil his fingertips popping out the two panels, but those panels are little 6kg slabs of carbon fibre and forged composite that look and feel cool.As Lamborghini's designer Felipo Perini demonstrated in a terrific live sketching session (a bit like Rolf Harris' Cartoon Time, a cultural reference that took some explaining to Felipo), this approach also allowed his team to preserve the Aventador's incredible profile completely intact. In fact, panels installed or stashed away under the bonnet, the Roadster looks even better than the Coupe, a rare accolade for any open derivative, never mind one as deliriously complex in form as this. Perini sketched a plan view, and the geometry of the Roadster's shape, and its engine cover in particular, easily stands comparison with some of the treasures in the company's back catalogue.There is a downside, but not one that's worth getting too hung up on\: the 0-100kph time is blunted slightly, and the Roadster needs a baleful 3.0 seconds compared to the Coupe's 2.9. The top speed is the same at 350kph, and though normal conversation is possible up to 130kph, you might need ear-plugs after that. And a good lawyer.The Aventador's 6.5-litre, 690bhp V12 remains an absolute marvel, a hymn to furious, single minded, normally aspirated internal combustion in a world that is hell-bent on adding turbos and, worse still, electricity to the equation. We had some track time, at Miami Speedway, which at least gave us the opportunity to tickle the V12's 8000rpm-plus red line, unleashing the elemental yowl that only 12 cylinders can deliver.Unfortunately, circuit work also serves as a reminder that the Aventador is not a natural athlete. It feels heavy and occasionally even a bit clumsy, and in Corsa mode - supposedly more track-oriented, but with the stability control still on - the electronics can't decide to go for a pre-emptive strike or to shut things down mid-corner. Either way, it's frustrating. Kill the stability control, and the Aventador isn't a total animal, and you have a clearer idea of what the chassis is really like, which is to say, it needs the sort of lively reflexes you'd probably imagine. The steering is great, but the car's throttle response is jumpy at the best of times and seriously trigger-happy in full attack mode. It's still super stiff, thanks to its carbon tub, though obviously not as rigid as the Coupe, and the ride quality is better resolved now.But the biggest glitch - and it is a big one - is the gearbox. Technical director Maurizio Reggiani admitted that the software had been recalibrated on the Roadster (and Coupe), to soften and smoothen the action, but fast up-shifts are still akin to being kicked in the head. Maybe Lamborghinis are meant to be borderline thuggish, but the transmission remains deeply flawed. In full auto mode around town, it's arguably even worse, a lurching throwback to the earliest days of semi-autos, when dinosaurs still roamed the land. Dual-shift gearboxes might be heavy and difficult to package, but once you've tried a good one there's no going back.Mind you, you forgive it the moment you get out of this car. It's a head-spinningly cool thing, a modern masterpiece of product design, and beautifully well made, too. The Roadster costs Rs 4.77 crore (ex-showroom, Delhi), and adds an extra layer of sensory overload to an experience that was hardly lacking in that department already. Ridiculously, that's arguably almost value for money in the private jet/super-yacht/Miami penthouse world it lives in.The Aventador's power, pace and appearance nudge it into the mega-money realm occupied by the Veyron, and the upcoming wave of Ferrari, Porsche and McLaren hypercars, while the 12C and 458 Spider are smaller and less expensive, and less exclusive. Yes, they're also both significantly more fun to drive, but the Aventador Roadster gets round that by smashing your senses in every possible way. Besides, you could always just look at it.