I found a 12% figure. Aerodynamics are a primary driver of range, which is a major ev selling point. A 12% drag decrease is huge, because you can carry less battery which means you can have a smaller motor, lighter frame, leading to even more range. So it would be very important if that is true.
The retractable door handle design allows radical aerodynamic designing for the side body panel. Retractable door handles are invisible handles that contribute by about 12% to reduce the drag coefficient of vehicles. Retractable door handles eliminate the issue of airflow bulge creation, air flow turbulence generation, and air flow pressure conservation. The decreased drag coefficient will also contribute to increasing the fuel efficiency of vehicles as there will be low drag generation resisting the movement of vehicles through the airflow. Amey Vikram, a lead analyst at Technavio for automotive components research