Porsche continues to introduce new 911 variants for 2013. The current 911 is based on the updated 991 platform that debuted with the Carrera and Carrera S in 2012. As with those models, in the new all-wheel-drive Carrera 4 and Carrera 4S the body changes are subtle but numerous, with larger LED main-beam projector headlamps fitted in higher front fenders, a wider rear end, a higher side waistline and all-new LED tail lamps. Two engines are available in 2013. In the Carrera and Carrera 4, buyers get a 3.4L horizontally-opposed direct-injected 6-cylinder that makes 350 horsepower. Carrera S and Carrera 4S buyers get a slightly larger 3.8L flat-six, which makes 400 horsepower. A variation of the 3.8L is also available on the all-wheel-drive Turbo and Turbo S models. Those models produce 500 and 530 horsepower, respectively, in both coupe and convertible form. Except in the Turbo S, all engines are mated to a standard 7-speed manual transmission. The 7-speed PDK double-clutch automatic is optional, and standard on the Turbo S. In the manual, the ratios are close together in every gear except 7th, which helps to achieve a better fuel consumption rate during highway use. Other features include electric power steering and a hydraulic decoupler of the front and rear sway bars, known as Porsche Dynamic Chassis Control. In addition, 911s feature a rear-wheel torque vectoring system that helps build traction using the rear brakes along with the rear differential. Inside, the 911 interior features styling touches consistent with Porsche's Panamera and Cayenne. There's no mistaking the design as something other than 911, however, with a host of gauges flanking a large tachometer, mounted front and center. The center console sports a large color touchscreen monitor for navigation and stereo functions. Several packages add features such as special sports seating, Bose audio, ambient lighting, auto dimming mirrors, and more. The Sport Chrono Package includes dynamic engine mounts, a dash-mounted analog and digital stopwatch, performance display, a Sport Plus button to control engine mapping and throttle response, and launch control for cars equipped with PDK.