In July, 2004, Porsche again unveiled another iteration of the 911 Carrera and 911 Carrera S models. Known as the Porsche Type 997, the car featured the same classic silhouette as all earlier variants of the Porsche 911, and included design cues – most especially a return to the clear, oval headlights with separate blinkers – that were found on older 911 models. While the Porsche 911 Type 997 featured a refined, race-inspired appearance, the car was hailed for being a true high-performance vehicle. The base Carrera featured a 3.6- liter boxer engine that produced an impressive 325 horsepower while the new 3.8- liter, six-cylinder engine found in the Carrera S produced an incredible 355 horsepower. In 2006 Porsche introduced the 911 Turbo, the first gasoline-powered production automobile to include a turbocharger with variable turbine geometry, a technology that allowed the aspect ratio of the turbo to be altered as conditions changed. They also introduced the next-generation Porsche 911 GT3. The new 911 GT3 was equipped with a 3.6 liter, naturally aspirated engine that produced 415 horsepower.