The Toyota Sienna (Japanese: トヨタ・シエナ, Toyota Shiena) is a minivan manufactured by Toyota at the Toyota Motor Manufacturing Indiana facility in Princeton, Indiana, United States, for the North American market. It is named for the Italian city of Siena, in the region of Tuscany. It replaced the first generation Previa van in 1997 with a more conventional front-wheel drive layout and shares a heavily revised platform with the Camry.^[1] Both the Previa and original Sienna were smaller than the other minivans they competed against, but a redesign in 2003 (for the 2004 model year) increased the dimensions to match those of its competitors.^[2] The Sienna is currently the only minivan in its class to offer all-wheel drive.^[3] It was redesigned a second time in 2010 (for the 2011 model year). The third generation Sienna went on sale in the United States in February 2010 and is the first Sienna to ever receive a "Top Safety Pick" award from the Insurance Institute for Highway Safety. Exports from the United States to South Korea began in November 2011.^[4][5]

In late 1997, Toyota launched the front-wheel drive 1998 model year Sienna in the North American market as a replacement for the mid-engined Previa. The Sienna debuted with a 3.0-liter 1MZ-FE V6 engine rated at 194 hp (145 kW) and 209 lb⋅ft (284 N⋅m) of torque. Built on an extended platform of the Toyota Camry, the Sienna was appropriately marketed as the "Camry of minivans," capitalizing on the Camry's popularity and reputation.

It came in three trim levels, CE, LE, and XLE. The LE and XLE models were equipped with 2nd row captain's chairs while the CE models came equipped with a 2nd row 2-passenger bench seat. The seats can be easily folded and individually removed as needed. The driver side sliding door and roof rack were standard on the LE and XLE models, but were optional on the CE models. The XLE models offered leather seats and a wood trim package. The Sienna also touted best-in-class fuel economy of 16 mpg city driving and 22 mpg highway driving. It was built in Georgetown, Kentucky. A year after its release, the Sienna faced new competition from the redesigned Honda Odyssey minivan, which was larger and offered a V6 like the Sienna.

In 2000, for the 2001 model year, the Sienna underwent a mid-cycle refresh. This update included a facelift to both front and rear fascias which added a redesigned front grille and bumper along with revised rear taillights sporting a more modern appearance (clear-lens turn-signals as opposed to amber-coloured). Toyota also revamped the center console area to add more usability to the HVAC controls along with new locations for the accessory switches (rear vent, power sliding doors, heated seats). The engine also came equipped with a variable valve timing feature VVT-i boosting output to 210 hp (157 kW) and 220 lb⋅ft (298 N⋅m) torque. The driver side sliding door became standard on all models, although the roof rack remained optional on the CE models.

This generation was noteworthy for its impressive safety content as one of the few minivans to offer options including front seat-mounted side torso airbags and Vehicle Stability Control. Anti-lock braking was standard. The Insurance Institute for Highway Safety rated the Sienna "Good" in all six frontal crash test measures, which was far better than the Previa.^[9]

The reputation of this generation was marred by a class-action settlement for an engine oil sludge problem which affected the V6 engines in many Toyota models. Symptoms of the problem include oil smoke in the exhaust, oil quickly becoming dark or black after an oil change, gasoline odor in the oil, high oil consumption, and eventually engine failure.

Toyota assigned Yuji Yokoya as chief engineer on the new Sienna project. Yokoya and his family drove the previous model over 53,000 miles (85,000 km) throughout North America to find weaknesses from the design.^[12][13] The engine was an updated ULEV certified 3.3-liter 3MZ-FE V6 paired with a new five-speed automatic transmission. The gear stick was moved from the steering column to the center console and had a gated shift pattern. Seating for eight was optional on lower-level trims, and the third row seating was fold-flat,^[14] allowing the van to transport 4 by 8 feet (1.2 by 2.4 m) building materials like plywood and drywall sheets.

On January 6, 2003, the second-generation Sienna was unveiled at the North American International Auto Show in Detroit.^[13] Production was moved from the Georgetown plant to Toyota Motor Manufacturing Indiana.^[13] Changes from the first generation included 45% more volume overall and 39% more cargo space. The seats were in the 60/40 split configuration, and the flat-folding third row seat was offered even with all-wheel-drive.^[1]

Trim levels, in order of increasing standard and available features were: CE, LE, XLE and XLE Limited (renamed Limited in later years). The most distinguishable difference on the XLE Limited model was the horizontal chrome bar placed above the rear license plate. The CE had a black trim there, while middling models had a body-colored trim.

Standard features included remote keyless entry, tilt-and-telescopic steering wheel, and high solar energy-absorbing glass (HSEA) on the windshield and front windows. All 2004–2007 Siennas had a factory tow package (hitch kit and trailer lighting connections not included) and a 3,500 pounds (1,600 kg) towing capacity.

All-wheel drive, optional on the more expensive trims included run-flat tires. The all-wheel drive system continuously divided engine power 50:50 front and rear.^[15]

Options, depending on the trim level, included HID Xenon headlamps, Dynamic Laser Cruise Control, parking sensors, a convex rear view mirror to enable the driver to see the passengers, a voice-activated navigation system (not voice activated for the 2004/2005 model year) which included a backup camera, 10-speaker JBL audio and rear-seat DVD entertainment system with two 110 V outlets.

New styling allowed for a drag coefficient of C**d=0.30. EPA Fuel economy was 17 mpg city driving and 23 mpg highway for the FWD version. The AWD version got 16 mpg city driving and 22 mpg highway driving. The turning radius was 11.2 metres (37 ft).

The Sienna came standard with anti-lock braking, brake assist, electronic brakeforce distribution, traction control and a tire-pressure monitoring system. Side torso airbags, and side curtain airbags were standard on certain 2004 and 2005 LE and XLE model trims while optional on others, but became standard on all 2006 trims. Vehicle Stability Control initially optional on lower trims became standard for 2008 models.

The IIHS gives the Sienna an overall "Good" score in their frontal offset crash test with "Good" marks in all six measured categories. All 2006 models and later receive a "Good" overall score, while pre-2006 models without side airbags receive an "Acceptable" score for side impacts.^[16]

The redesigned 2011 Sienna premiered at the Los Angeles Auto Show in early December 2009. It was designed at Calty studios and engineered at Toyota Technical Center in Ann Arbor, Michigan and Toyota Motor Corporation in Japan.^[23] The new Sienna arrived at dealers in February 2010.^[24]

The Sienna is offered in five trim levels, the Sienna base grade, LE, XLE, Limited and for the first time the SE trim. The new SE offers revised bodywork, clear tail lamps, 19-inch (480 mm) wheels, firmer suspension and revised steering tuning for a sportier ride. All-wheel-drive is only available with the V6 engine on the LE, XLE and Limited model trims. Described by AOL Autos as slipping a sports car in a minivan, Chief Engineer Kazuo Mori (an avid autocrosser) reportedly had to overcome opposition to get the SE equipment package included in the line-up.^[25]

The previous 3.5-liter 2GR-FE continues, but for the first time the Sienna offers a four cylinder engine, the 1AR-FE; and is the first time Toyota has offered a four-cylinder engine in a North American minivan since discontinuation of the Estima/Previa in late 1997. An Electric Power Steering (EPS) system replaces the previous hydraulic power steering system. Toyota continues to offer all wheel drive in the Sienna. It is the only North American minivan with an available AWD drivetrain.^[26] Toyota expects EPA-estimated mileage figures of 19 mpg‑US (12.4 L/100 km) city / 24 mpg‑US (9.8 L/100 km) highway for models powered by the 4-cylinder engine, 18 mpg‑US (13.1 L/100 km) city / 24 mpg‑US (9.8 L/100 km) highway for 2WD V6 models, and 16 mpg‑US (14.7 L/100 km) city / 22 mpg‑US (10.7 L/100 km) highway for AWD models. An optional tow package for V6 models is rated to tow 3,500 pounds (1,600 kg).

The front dashboard features a "swoop" wood trim, inspired by the Toyota Venza and Lexus RX, that gives front seat occupants a "60/60" split whether in the driver or passenger seat.^[25]

New features include an optional sliding second row with "Lounge Seating" recliner style chairs, a feature previously seen on the Lexus LS,^[27] and Toyota's keyless Smart Key System with push-button start. The rear seat entertainment option now uses a 16.4-inch (41.7 cm) LCD screen which operates in two view modes, a single 16:9-ratio widescreen or two separate 4:3-ratio split screens with separate wireless headphones.

For safety the back-up camera comes with a new 180° panoramic view. Other new options include a Pre-Collision System (PCS) as well as an automatic highbeam dimmer, Safety Connect and a more advanced stability control system known as Vehicle Integrated Dynamics Management. A driver's knee airbag is now standard as well.

When the second row seats are removed, the bottom of the second row seats, which is similar to a rack, remains attached to the van floor. This means that with second row seats removed, the floor is not flat.^[28]

Toyota is the first automaker to offer a factory installed auto-access seat for disabled people. The one-touch rotating, power ascending/descending lift-up seat can lower to within 19 inches (48 cm) of the ground.^[29]

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