Toyota's minivan is redesigned for 2004 with available head-protecting curtain side airbags, hideaway 3rd-row seat, and all-wheel drive. Styling is new and the '04 grows 5.1 inches in wheelbase, 6.5 inches overall, 3.9 inches in width, and gains about 200 lb. It ascends through CE, LE, XLE, and new leather-trimmed XLE Limited models. Front-wheel drive is standard. AWD is available on all but the CE and comes with run-flat tires. A 230-hp 3.3-liter V6 replaces a 210-hp 3.0. A 5-speed automatic supplants a 4 speed as the sole transmission, and the shift lever is now on the lower-center dashboard.

All Siennas have ABS, tilt/telescopic steering wheel, remote keyless entry, tire-pressure monitor, 3500-lb tow package, and rear air conditioning. Standard features include power windows for the dual sliding side doors. LE offers an optional power right-side sliding door. XLE and Limited have dual power doors and a power liftgate. All models come with 2nd-row buckets for 7-passenger seating. CE and LE can carry 8 passengers via an optional 2nd-row bench whose middle section is sized for a child-safety seat. The standard 60/40 split 3rd-row bench seat folds into the floor.

Limiteds and AWD versions have 17-inch wheels vs. 16s on other models. The Limited also adds antiskid/traction control, xenon headlamps, front/rear-obstacle warning, and radar cruise control. Head-protecting curtain side airbags cover all outboard occupants and are standard for Limited, as are front torso side airbags. Other models offer packages that bundle the airbags with various features. Rear DVD entertainment and a navigation system are also available.