It's all about the noise. How the mighty 1200-hp W-16 growls like a badly hungover grizzly bear when you punch the gas pedal. The psychotic calliope routine from the four turbochargers as you change gears, a cacophony of chuffs and puffs, whooshes and whistles right behind your head that sounds like you're about to be run over by the 20th Century Limited. And the white-noise roar of the wind over your head as you effortlessly blow through the 200-mph barrier, headed, like a ground-based Chuck Yeager, for the outer limits of road car performance.

The Grand Sport Vitesse is the ultimate Bugatti Veyron experience, in shattering 7.1 surround sound.

In simple terms, the Vitesse is a Veyron Grand Sport convertible that's been given the Super Sport treatment. In addition to 1200 hp at 6400 rpm, its 8.0-liter W-16 delivers a herculean 1106 lb-ft of torque from 3000 to 5000 rpm, courtesy of the same bigger turbos and intercoolers as the Super Sport, and, because you need more fuel as well as more air to make more power, the same quad fuel pump setup. And boy, does this thing have an appetite: Bugatti engineer Jens Schulenburg claims that at full throttle the Super Sport/Vitesse engine will consume more air in one hour than a human does in a month, though that statistic is purely academic, because at full throttle the Vitesse's W-16 will gulp through an entire tank of gas -- 26.4 gallons -- in just eight minutes.

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But there are subtle differences between the Super Sport and the Vitesse. Removing the roof changes the way the air flows around the car, and in a car with the Veyron's V-max, that demands you pay attention to aerodynamic details. The rear spoiler, for example, knows whether the detachable hardtop is on or off the car, and so changes its angle of attack to ensure it delivers the same level of downforce at high speeds (with the roof off, the Vitesse is limited to a mere 233 mph; roof on, it will hit 255 mph). The rear differential oil cooler has been moved from the right-hand side of the car to under the rear diffuser, and the spring rates have been softened slightly to compensate for the reduction in body rigidity.

As you'd expect, the Grand Sport Vitesse is staggeringly fast -- in addition to its stratospheric top speed, Bugatti claims a 0-60 mph time of less than 2.6 seconds, and a quarter-mile time of 10.0 seconds. It says the Vitesse will reach 124 mph from a standstill in just 7.1 seconds, and 186 mph in 16.0 seconds. What does that feel like? Like a Nissan GT-R on LSD. While the GT-R's acceleration to 100 mph is impressive, the Bugatti maintains the same relentless thrust way beyond 200 mph. Nail the gas in the Vitesse at 160 mph in fifth, and it responds like a regular Corvette or Porsche 911 might at 60 mph in third gear. It's truly, truly staggering. Especially for a car that weighs almost 4400 pounds.

Simply put, the Vitesse alters the way you perceive the world. See a straight on any regular road, think of a number, and double it. That's the speed at which the Vitesse will be traveling when it arrives at the next corner. And that's no problem, because you simply hammer the carbon-ceramic brakes and the Vitesse stops. Just like that.

First will take you to 65 mph, second to 92 mph, and third to 122 mph, so the Bugatti will simply annihilate regular traffic, shrinking safe passing zones to absurdly small parcels of space and time. Push hard through the twisties, and the handling devolves into mild understeer; the trick to canyon road cut-and-thrust in this car is to be just a little patient with the gas, and feed it in as you exit the turn. Get it right and you can feel a subtle change in the weighting of the steering as the Haldex system funnels more torque to the rear tires, and you know you've nailed it when you sense the massive 365-710 ZR 540A Michelins nibbling at the limits of adhesion as you power away from the apex. Attacking a series of fast, open sweepers in the Vitesse is almost a religious experience.

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At normal speeds -- mooching through town, or cruising on the freeway -- the Bugatti has the same easy drivability of the GT-R; in fact, it feels smoother and more refined than the edgy Nissan. The Veyron's seven-speed dual clutch automated manual transmission -- developed and built by British engineering company Ricardo -- is more accomplished, and the ride is more compliant.

And that's the utter genius of the Grand Sport Vitesse: For all its staggering power and performance, it's no hairshirt hypercar. You don't have to wrestle it into submission to drive it fast, and grit your teeth when you drive it slow. You can go 200 mph with the roof off without mussing your hair, and you can crawl at 2 mph in summer traffic along the Boulevard de la Croisettes in Cannes in air-conditioned comfort. There are some who suggest that because the Bugatti Veyron is so user-friendly it is somehow less of a car. They're wrong. The Veyron is extraordinary, in every way. And the Grand Sport Vitesse might be the most extraordinary Veyron of them all.

How Fast Can a Veyron Go?

Former racer Pierre-Henri Raphanel, Bugatti's official test driver and quite possibly the world's bravest man, says the only thing preventing the Veyron from going beyond 270 mph is tires. Raphanel, who set a production car record top speed of 268 mph in a Veyron Super Sport at VW's Ehra-Lessien test track in July, 2010, says Michelin runs the Veyron's massive meats on its tire test dyno at 270 mph -- the fastest it can spin -- for 20 seconds, then at 250 mph for 20 seconds. It repeats that cycle two more times. Then the tires explode.

VW engineers made Raphanel run both directions along the 5.6-mile straight on the eastern side of the Ehra-Lessien track to get the record, because they knew the Super Sport's tires could not handle the g-loading on the gently curved western section at V-max. Michelin will only allow two sets of tires -- they cost about $42,000 a set -- be fitted to the Veyron before the rims -- $69,000 a set -- also have to be replaced to ensure the integrity of the bead seal at high speed.

Tires are why the Grand Sport Vitesse's 255 mph top speed is artificially imposed, confirms engineer Jens Schulenberg. Engine power is not the problem: "We could go faster," he says. Gulp.

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