The Panamera is offered in six versions, the rear-wheel drive 2 and S, and the all-wheel drive 4, 4S, Turbo and Turbo S. The 2 and 4 models come with a direct injection 3.6-liter V6 300-hp engine while the 4, 4S and Turbo feature the larger 4.8-liter V-8; the S and 4S models making 400-hp, the Turbo adds twin-turbocharging for 500-hp, and the Turbo S bumps that up to 550. The Porsche PDK double-clutch gearbox is the only transmission choice, and all models are equipped an auto start-stop feature for increased urban fuel economy. The body appears to be a four-door sedan but with a coupe-like profile and a power liftgate, rather than a typical trunk, for access to the spacious luggage area. Standard safety features include ten airbags, bi-xenon adaptive headlights with LED daytime running lights, rain sensing wipers, full LED rear lighting, four belt pretensioners and electronic traction and stability control. A small sample of optional tech features includes a 6-disc CD changer, Bose surround sound, Burmester surround sound, front and rear ParkAssist, an electronic logbook and voice control. For 2012 the Panamera has added a Turbo S model that includes 50 more horsepower and standard 20-inch wheels.