Sorry, no! It is designed to ADD more friction to the system and to recover a bit of what it ADDED to begin with.
It really depends on how much air resistance there is in the car to begin with. The more resitance the more likely it is to convert some back into energy. His design looks inefficient to begin with so I think there is a chance to capture energy here. Say you had a flat cross-section with 100% reistance and then compared it to a flat cross-section with a hole in it where a turbine was mounted. You would both reduce air resistance to some extent and increase energy capture by driving the air past the turbine. But the less resistance you have to start with in the body design, the more likely you are to add resistance by adding on a turbine.