Using a scan gauge(s) to monitor various items in my (new to me) 2016 Hybrid. It appears that the rear motor engages at every start from a stop position and quickly cuts out at around 15mph during my light foot driving. I have not really tested this on the interstate or at high speeds. My previous hybrid vehicle (non-Toyota) had a 4wd setup and also engaged the rear wheels at every start from stop and also when one pressed on the gas pedal at any speed. Need more time driving the vehicle to figure out about how much torque is needed at various speeds.