That's really fun!
*it's like the 15-mph tailwind/'turbine' is the Savonius rotor
* which 'starts' the 27.7-mph 'Darius rotor' impeller.
*the whole car's mass is a flywheel
*the lift generated from the spinning airfoil provides the thrust for acceleration
*the rear axle fairing and venturi between the vertical turbine supports enhanced horizontal 'lift'.
*top speed is reached when lift = drag
*Exquisite!