If you think 270 mph in a convertible is a good idea, there's probably only one car that comes to mind: the upcoming Bugatti Veyron Grand Sport Super Sport. That's really the only supercar out there that could possibly deliver that blend of world-record-level speed and open-air touring.

Or it was the only car in that category until Hennessey announced a convertible version of its Venom GT for a 2012 debut.

The standard Venom GT hasn't actually set a world speed record like the Bugatti Veyron Super Sport, but Hennessey does list its top speed north of 270 mph.

As you probably recall, the car is a kind of Frankenstein among supercars--a tiny Lotus chassis fitted with a not-so-tiny twin-turbo LS9 V-8 engine. It weighs in at around 2,640 pounds and offers 1,200 horsepower on tap, giving it one of the most lusty power-to-weight ratios in the game.

The Venom GT Spyder will offer the same 1,200-horsepower twin-turbo V-8, so it will certainly offer much of that same top-end performance. Whether you want ballistic asphalt obliteration or a relaxed, open-air tour on a sunny day, the removable top on the Venom GT Spyder will allow you the luxury of both.

"With the hardtop in place, the Venom GT offers a very visceral, raw, driving experience", company CEO Don Goldman explained in a statement. "With the hardtop removed, the wind and the growl of the twin turbo V8 will offer our clients an even greater driving sensation."

Hennessey will offer just five 2013 Venom GTs with deliveries beginning next summer. Customers will be able to order the car with either a fixed or removable roof. The Spyder model will sell for $1.1 million, a $150,000 premium over the hardtop. Two lucky customers have already snagged the first two models.