The new rear-wheel-drive road rocket will debut publicly at the Moscow auto show in late August and will go on sale in the United States in October. Sticker price: $245,000.

The GT2 RS, to be built in a limited run of 500, is powered by the latest evolution of Zuffenhausen's 3.6-liter, twin-turbocharged, horizontally opposed six-cylinder engine, tuned to deliver a Le Mans-grade 620 hp. That's 90 hp more than the out-of-production 911 GT2 and 8 hp beyond the German carmaker's previously most powerful road car, the 5.7-liter, naturally aspirated V10-powered Carrera GT.

The Metzger engine, named for the motorsport engineer responsible for its original design, eschews the direct injection of Porsche's newer 3.8-liter six-cylinders for an older sequential fuel-injection system, boosted by the latest BorgWarner turbochargers.

Drive is channeled to lightweight, 19-inch, center-bolt, forged-alloy rear wheels via a beefed-up six-speed manual gearbox and a mechanical locking differential backed up by a recalibrated stability program.

With a series of weight-saving measures, including a carbon-fiber hood and rear wing and interior features such as racing bucket seats, the 911 GT2 RS tips the scales at 3,014 pounds--154 pounds less than the three-year-old 911 GT2. Aerodynamic upgrades include a 0.4-inch-taller rear wing, providing added rear-end downforce, and widened front fenders to accommodate a wider front track.

Although it's not the fastest-accelerating 911 of all time, the 911 GT2 RS's performance is still extraordinary. Porsche claims 0 to 62 mph in 3.5 seconds (0.2 second faster than the 911 GT2), 0 to 124 mph in 9.8 seconds and 0 to 186 mph in 28.9 seconds. Top speed is 205 mph at redline in sixth gear.

A unique chassis setup that includes Porsche Active Suspension Management, with variable damping control, provides added agility.

Porsche claims that the 911 GT2 RS lapped the Nurburgring in 7 minutes, 18 seconds--19 seconds quicker than the new 911 Turbo S. That's a time that would give it No. 1 billing among series production cars on standard road tires at the legendary German circuit.

Watch driving footage of the 911 GT2 RS below. There's no sound, but interactive editor Dale Jewett says make your own awesome music video by cueing up Ted Nugent's "Stranglehold" for background music.