The second generation Toyota Sienna debuted at the North American International Auto Show in early 2003 as a 2004 model. Built on a heavily revised platform, the vehicle expanded substantially in all physical dimensions, boasting a 3,030 mm wheelbase and a 45% increase in total cargo and passenger volume. Exterior aesthetics shifted toward a more muscular and modern silhouette with large swept-back headlights and prominent body creases. The refined cabin introduced powered dual sliding doors, a power liftgate, and an innovative Split & Stow 3rd Row seating mechanism that folded flat into the rear floorwell.

Initial powertrains featured a 3.3-liter 3MZ-FE V6 engine outputting 230 horsepower mated to a new five-speed automatic transmission. A mid-cycle refresh for the 2006 model year updated the front grille, lighting elements, and gauge cluster, followed by the introduction of a potent 3.5-liter 2GR-FE V6 engine producing 266 horsepower for 2007. A defining competitive advantage of the XL20 series was the option for full-time all-wheel drive (AWD), making it one of the few all-weather family minivans available in North America.