i have observed the same thing on my car.
i found a cfd picure that shows what goes on, because of the similar observations i think this happens on most vehicles of this layout.
i suppose this is why the shape of the A pillar is more important than one would guess at first glance.
it seems a somewhat complex effect, and i can't really juge if it's good or bad or where the air should go ideally ( i suppose over the car). but it's interesting to note the airflow seems to originate over the side of the hood, and after it's trip over the sidewindow seems to return to the roof.
perhaps another reason why roof racks might hurt FE!