The rear-steer system uses two electro-mechanical actuators to deliver up to 1.5 degrees of steering input, depending on speed. At speeds up to 50 km/h (about 31 mph) the system steers in the opposite direction to the front wheels to enhance rotation. Above 80 km/h (about 50 mph) the system steers in parallel to the front wheels, virtually extending the wheelbase by 500 mm (about 19.5 inches) for greater high-speed stability. The steering input to the rear axle at high speeds also increases the slip angle much more quickly, giving the driver better feedback about the limits of the tires and allowing quicker transitions.
The new 911 GT3 also rides about 30 mm lower than the standard Carrera, and the suspension includes two PASM maps just like the previous GT3. New suspension designs at the front and rear of the GT3 improve geometry and at the same time shave about 9 pounds from the car's weight.
The 475-horsepower, 3.8-liter, flat-six-cylinder engine revs to a glorious 9,000 rpm thanks to a completely redesigned valvetrain, and is accordingly paired with new shorter gear ratios in the standard PDK transmission, which should allow for maximal performance under a greater range of conditions.
Otherwise, the GT3 is about what you'd expect: new 991 size and proportions, a big fixed wing, and GT3 badges. A fully-variable limited-slip rear differential, 20-inch center-locking forged alloy wheels, and 44 mm wider rear track (compared to the Carrera S) round out the package.
The 2013 Porsche 911 GT3 will launch in late 2013 in the U.S., at a price of $130,400 plus $950 in destination fees. Look for more specifics after the car's debut at the Geneva Motor Show tomorrow.