McLaren unveils 675LT Spider 'Longtail' [Video]

The hardtop 675LT quickly sold out, but 500 buyers will now have a chance to buy the convertible edition.

McLaren has introduced the 675LT Spider, bringing an open-air experience to the limited-edition 'Longtail' model.

Like its hardtop counterpart, unveiled in Geneva, the Spider pays homage to McLaren's F1 GTR race car of the '90s. The new Longtail coupe sold out within two months, before the first unit rolled off the assembly line, prompting the company to build another run in a Spider body style.

The Super Series' 3.8-liter twin-turbo V8 has been outfitted with new turbos and lightweight components. As the model name implies, output has increased to 675PS (666 horsepower) and 516 lb-ft of torque.

The extra power makes the 675LT Spider McLaren's fastest open-top model ever, accelerating to 62 mph from a stop in just 2.9 seconds and rocketing all the way to 124 mph in 8.1 seconds. The latter figure represents a penalty of just 0.2 seconds below the coupe, which is both lighter and more aerodynamically optimized.

To keep weight to a minimum, engineers chose carbon-fiber to build many body panels. Lightweight components were also added for the chassis and powertrain, resulting in a dry curb weight of 2,800 lbs -- approximately 220 lbs under the 650S Spider. It weighs only 88 pounds more than the 675LT coupe.

All of the extra heft is associated with a retractable three-piece hardtop roof system, which can be stowed while underway at speeds up to 19 mph.

Aside from the cosmetic and powertrain tweaks, the 675LT models are built with the most track-focused suspension setup of any Super Series model. Front and rear spring rates have increased by 27 percent and 63 percent, respectively, while downforce has jumped by 40 percent compared to the 650S Spider. The car sits on a slightly wider front track, with 19-inch wheels up front and 20-inch wheels out back.

Like the coupe, only 500 examples of the 675LT Spider will be produced. Production is expected to begin in summer 2016, but each unit will likely be called for ahead of assembly.