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I never thought of "ram air" when talking about the scoops. In the BMW case, I'd like to think that the scoops may help avoid stalling of the air in the intake tract.
On [recent] BMWs, the air intake is angled 90 degrees down and presents as two holes in a plane. Imagine for a moment that the engine is off, and not sucking in air. If the car is moving forward (despite the engine being off) - especially faster - the air rushes past these openings. With my limited knowledge of fluid dynamics, I think this could cause stalling of the air and essentially creating a vacuum in the intake tract. Now of course the engine running causes negative pressure in the intake and thus sucks in air - even against the stalling force.
Based on that (quite possibly flawed) assumption, I could imagine that the air scoops actually redirecting incoming air upwards, would aid in airflow by reducing the stalling/slowdown of incoming air.
Again, quite possibly wrong, but just my $0.02...
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