E-four

E-Four (short for Electrical 4WD System),[1] eFour, AWD-i, or AWD-e was developed by Toyota.

Amount of torque transferred to the rear wheels is automatically adjusted by the vehicle's electronic control unit according to driving conditions.

[2] In North America, Toyota uses the term AWD-i (All-Wheel Drive with Intelligence).

The compact HV4WD E-Four used for the Prius adds little weight and does not reduce the fuel economy or interior storage.

A few weeks before the November 2018 Los Angeles Auto Show, Toyota issued a press release with text and images featuring the car in snowy conditions, suggesting the E-Four package would likely debut in the 2019 U.S. model at the show.