The third-generation of the world's best-selling hybrid arrived in Detroit with more of everything that matters: sleeker looks, added creature comforts, upgraded performance and even-better fuel economy. Cleaner styling on this five-door yields a 0.25 coefficient of drag, lowest of any production car today. The Prius' well-appointed cabin boasts a more sophisticated appearance and additional people/cargo space. Its larger 1.8-liter engine and redesigned Hybrid Synergy Drive system now make 134 combined horsepower. But despite 24 more ponies and quicker acceleration, its average fuel economy is boosted from 46 to an estimated 50 mpg. The coolest new option is a glass moonroof with a solar-powered ventilation system, but voice-activated navigation, Dynamic Radar Cruise Control with Lane Keep Assist and a Pre-Collision System also are available on this yet-unpriced Prius, which goes on sale in the spring.