A Closer Look at the All-New 2021 Toyota Sienna's Versatile Hybrid Powertrain

The fourth generation of Toyota’s popular minivan aims to redefine the segment offering a host of new and enhanced features, chief of which is a hybrid powertrain available as standard across all trims.
2021 Toyota Sienna 9 photos
Photo: Toyota Motor Company
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Designed, engineered, and assembled in the U.S., the new model built on the GA-K platform was unveiled online in May 2020. It promises to raise the bar for style, safety, comfort, and fuel efficiency in its segment while retaining the versatility and capability that made it so popular in North America.

Toyota called the previous generation a “swagger wagon,” and the all-new Sienna takes that to a whole new level. It does that by offering an experience that draws inspiration from the Highlander, making drivers feel like they are driving a capable SUV, rather than a traditional minivan.

The 2021 Sienna was designed by the joint effort of CALTY’s Newport Beach, California and Ann Arbor, Michigan studios with the goal of delivering a combination of room, comfort, convenience, fuel efficiency, and versatility previously unheard of for this segment.

2021 Toyota Sienna
Photo: Toyota Motor Co.
The new Sienna features a host of new premium features, including kick-open and closed sliding side doors and rear gate, four-zone climate control system, a segment-first power tilt and telescoping steering column with heated steering wheel, digital rear-view mirror, 10-inch head-up display, and a 12-speaker JBL Premium Audio system.

However, the most groundbreaking addition is the hybrid powertrain that pairs the high-efficiency 2.5-liter DOHC four-cylinder engine along with two permanent-magnet synchronous motors to provide 243 hp (181 kW; 246 PS) and return a benchmark-setting manufacturer-estimated 33 MPG (7.1 liters per 100km) combined fuel economy.

The gas engine offers a thermal efficiency of 41%, one of the highest of any ICE-powered automobiles on the market. It uses Toyota’s innovative variable valve timing-intelligent system by electric motor (VVT-iE) on the intake camshaft, and the established VVT-i technology on the exhaust camshaft. It also packs an electric water pump and thermostat as well as a fully variable oil pump.

For added convenience, the powertrain does not require conventional recharging from an external power source. The Toyota Hybrid System II charges the battery pack automatically as the vehicle drives using regenerative capabilities.

This offers the same gas-and-go experience and power as previous models, requiring fewer stops to refuel, thanks to the smaller, more efficient, and environmentally-friendly powertrain.

2021 Toyota Sienna
Photo: Toyota Motor Co.
Drivers can use the sequential shifting feature to “downshift,” which increases the regenerative braking capabilities and recharges the battery. Sienna’s hybrid system also enhances ride smoothness and handling by providing electronic torque vectoring.

Performance and efficiency can be controlled through four driver-selectable modes. EV allows electric-only driving at low speeds for short distances; Eco can be used to maximize fuel and battery efficiency; Normal is designed to balance performance and efficiency for everyday driving; and Sport boosts acceleration and offers agile handling.

A 7-inch display built in the instrument panel includes a Hybrid System Indicator that shows system output and regeneration status, encouraging eco-driving through a video game-like scoring function.

2021 Toyota Sienna Interior
Photo: Toyota Motor Co.
The all-new Sienna continues to offer optional all-wheel drive, being the only vehicle in its segment that combines a hybrid powertrain with AWD. The new system is called Electronic on-demand AWD and ditches the conventional transfer case and driveshaft layout in favor of an additional electric motor that powers the rear wheels.

It distributes torque dynamically, as required by driving and road conditions, promising to prevent front-wheel slip, reduce understeer, and offer a safer driving experience.

The 2021 Sienna is available in Toyota dealerships nationwide, with prices starting at $34,460. Apart from the hybrid powertrain, it brings advanced safety features like Toyota’s Safety Sense 2.0 suite or blind-spot monitoring as standard on all trims. It also retains the towing capabilities of previous models, being able to haul up to 3,500 pounds (1,588 kg).
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About the author: Vlad Radu
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Vlad's first car was custom coach built: an exotic he made out of wood, cardboard and a borrowed steering wheel at the age of five. Combining his previous experience in writing and car dealership years, his articles focus in depth on special cars of past and present times.
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