https://www.cnet.com/roadshow/news/aston-martin-rapide-e-shanghai-motor-show/

Speaking of aerodynamics, without the need to accommodate exhaust piping, the Rapide E's entire undertray has been optimized to reduce drag. The lack of exhaust tips also makes room for a larger rear diffuser that is "now wholly dedicated to aero efficiency."  Meanwhile, the forged aluminum wheels have been redesigned for reduced turbulence and even the bespoke Pirelli P-Zero tires reduce rolling resistance. All in, the electric Rapide E cuts through the air with 8-percent less drag than the gasoline model.

The fully electric Rapide E is motivated by twin electric motors. However, rather than driving the rear wheels independently, the motors send their combined 601 horsepower and 701 pound-feet of torque through a single-speed transmission and a mechanical limited-slip differential at the rear axle. My guess is that configuration has a lot to do with the Rapide's platform not being originally designed for an electric powertrain and there just not being room on the rear axle for two e-motors.