220mph in the Pagani Huayra prototype The two-footed assault on the Huayra's nose is, it transpires, a scientific procedure to check its new front splitter won't fall off and cause a spectacular accident. Satisfied the splitter is stuck on enough to prevent the Huayra becoming a very expensive ground-to-air missile, the man ambles off with a non-committal thumbs up. This does not alleviate my sense of foreboding. Why is TopGear here? Well, this may sound obvious, but if you're going to sell a 220mph+ car, at some point it has to go over 220mph for the first time. And for all your wind-tunnel testing and computer modelling, that's the point at which you have to let your baby run free and trust that a wheel or, say, a splitter, isn't going to pop off at triple-figure speeds, reducing your priceless prototype and slightly less priceless test driver to a flesh-and-carbon-fibre schnitzel 220mph in the Pagani Huayra prototype Generous souls that they are, the gents at Pagani asked if TG would like to ride shotgun during the almost-ready Huayra's first shot at 220mph on the high-speed ring of a top Secret test Facility that, for reasons of confidentiality and wanting to remain attached to our vital danglies, we cannot name. Suffice it to say that you definitely haven't seen it featured in any recent episodes of TopGear telly. Davide Testi - chief Pagani test driver, and the man who'll get a very angry letter from my mum if this all goes wrong - hops into the driver's seat, pops down the Huayra's gullwing door and swings us languidly towards the banked, four-lane ring. I rip the gaffer tape off the Huayra's glovebox and delve inside to extract a tiny digital video camera. I am now a felon. 220mph in the Pagani Huayra prototype You may have spotted that this feature contains precisely zero photos of a Pagani Huayra charging round a banked ring at obscene speeds. that is because another manufacturer, which may or may not hail from the Stuttgart region of Germany, is testing its own top-secret supercar at the same time and has banned any cameras from inside the proving grounds on pain of efficient teutonic death. Unfortunately, TopGear only discovered this a couple of hours ago, when, after shooting the prototype Huayra alongside a finished version out on public roads (hey, why have one million-quid hypercar when you can have two?), we cheerily rocked up at the front gates of the top Secret test Facility with a Fiat panda full of shiny camera gear. 220mph in the Pagani Huayra prototype This caused a deal of shouting and anger. As the security heavies started to root through his camera kit, photographer Justin - in a rare moment of subtlety - backhanded a tiny video camera into my jacket pocket before being shepherded into a windowless interrogation chamber by a burly man with a pair of rubber gloves and a cruel smile. The camera and I made it behind enemy lines, so it is down to my shoddy videography skills to provide either (a) proof of our glorious high-speed run or (b) vital evidence to the impending coroner's inquest. We swing out onto the 12-mile bowl, and Testi floors it. The speedometer is rated in kilometres per hour, and 354kph is the magic number: 220mph. In three seconds, we are doing 100kph (62mph), and the Huayra is just getting started. This car has already racked up 300,000 miles in testing; it doesn't feel like it. I watch the needle surge up past 200kph - 124mph - in the time it'd take a hot hatch to hit 62mph. Just as I'm thinking, "Ach, maybe this won't be so dramatic...", Testi tugs the wheel violently to the left. We dive across two lanes and my head slams against the Huayra's window. He tugs the wheel to the right and a whimpering noise emerges from somewhere within my head. "Warming the tyres," he grins. Testi slams the throttle again, and the speedo grabs for the 300kph (186mph) mark. 220mph in the Pagani Huayra prototype The acceleration is preposterous - a kerbweight of 1,350kg, over half a ton less than a Veyron, and a twin-turbo V12 churning out 750bhp will do that - but the Huayra's power never seems in danger of overwhelming its rear tyres. That's partly because they're 355-section monsters, but also because the Huayra doles out its power with astonishing linearity. Company boss Horacio Pagani was adamant the AMG-built engine shouldn't simply chase huge horsepower figures with a couple of pumpkin-sized turbos and to hell with the drivability, so commissioned a team of 65 AMG employees to work flat-out on the 6.0 V12, ensuring its responses matched those of a naturally aspirated engine. So far as we can ascertain, they nailed it.

I am sweating nervously in the passenger seat as prototype Huayra Number Three is brimmed with fuel, when a man wanders over and starts jumping up and down on the car's nose. Violent, full-force leaps, again and again. This is not what you want to see a couple of minutes before you're set to ride along on an untested hypercar's maiden voyage towards 220mph. Words: Sam Philip Pics: Justin Leighton This feature first appeared in the April 2012 issue of Top Gear magazine