Certainly does reduce drag. Look at the frontal area of the sidepods, in this case smaller is better. Also helps with with the coke-bottle shaping too.
BTW, nice sketches in the story and with historical reference. Seems like the configuration games are to work with the incoming airflow. I would guess that the external aero works also to get the flow 'aligned' properly for the new radiators (or they are simply taking advantage of somthing they've observed in the windtunnel and/or CFD).
Renault were the first to introduce this radiator solution. Sauber have just copied what they deemed to be an efficient compromise between aerodynamics and cooling.
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