The down force of the vehicle should be controlled to reduce drag and rolling loss. The simplest control I can see is adjustable height on the rear suspension. When cruising on the highway the rear suspension can lower making the cars aero profile very close to neutral with respect to down force. Under emergency braking, lower speed operation and sports mode the rear suspension can be raised to create more down force.
Adjustable downforce might be necessary. Mercedes made once an extremely aerodynamic Le Mans car. The problem was that under certain circumstances the car started to take off, which was rather uncomfortable at high speeds.
I'd have to know more how the aero behaves the way it is now before thinking about active aero controls. I need more data than just looking at the pictures. I'm sure they've done modeling and driven the prototype and have a better idea of what it does in real life. Any opinion I have on downforce, lift, tailwind or crosswind performance is little more than a guess.