A slotted or Fowler flap is far superior to a smooth surface "morphed" flap. So is a plain flap that is aerodynamically balanced at 27-32 degrees flap MAC. On the Carbinliner, we use a plain flap because the flapped L/D ratio is not important below 450 mph on a car designed to go 550. At 500-550, the wing is designed for the required downforce with the flap fully in trail; i.e. zero degrees of deflection. At lower speeds the flap is deflected which results in higher negative lift coefficients which match the lower dynamic pressure (the multiple of which is flat downforce from 200-550 mph). Yes, it's not as "efficient" at lower speeds. It doesn't matter, the speed is lower so the flat plat drag times the dynamic pressure (D/q) is lower despite the flap deflection.
The wing design is optimized for high speed, the flap creates traction at lower speeds for acceleration. All commercial and business aircraft are designed this way with the wing designed for high speed and the flaps designed to provide greater lift at the expense of drag at low speed where drag matters less.