The third generation Toyota Prius debuted as a compact liftback manufactured and marketed by Toyota, having launched in 2009 for model year 2010 at the January 2009 North American International Auto Show. Internally designated as model XW30 and replacing the XW20 series, sales began in Japan on May 18, 2009. Noted for its more aerodynamic bodywork and a claimed drag coefficient of Cd=0.25, an underbody rear fin helps stabilize the vehicle at higher speeds. The third generation is also noted as the first production engine without efficiency-robbing accessory drive belts.