E-four

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E-Four is Toyota’s electric all‑wheel‑drive system. The front wheels are powered by the hybrid gas‑electric powertrain, while the rear wheels get power from a dedicated electric motor with its own control unit, reduction gear, and differential. The car’s computer automatically adjusts how much torque goes to the rear wheels based on driving conditions, and it adds regenerative braking. In North America this system is called AWD-i (All‑Wheel Drive with Intelligence). There is no driveshaft between the front engine and rear wheels; the rear wheels are powered only by the rear electric motor(s).

E-Four first appeared in the 2001 Estima Hybrid and is used in several Toyota and Lexus models, such as the 2016 RAV4, Lexus NX 300h, RX 450h, and Prius AWD-e, and it may be used in the fifth‑generation Prius. In Japan, the all‑wheel-drive Prius has been available since 2015 and costs about $1,700 more. The lightweight HV4WD version for Prius adds little weight and does not reduce fuel economy or cargo space. Toyota signaled a 2019 U.S. debut of E-Four at a late‑2018 press event.