Good morning,

first of all, thanks a lot for the feedback. It's mucho appreciated

@ gillbrooks: the shadow comes from the roof of the building above the glass colums. I guess I'll better remove that for this scene.

@ ShawnDriscoll and silverblade: I've changed the atmosphere to GR and dialed in about 50% Shadow density in the light editor. I still have to keep the fill-lights for the car and the girl, but the result is much better.
I didn't like the floor with 5% reflection, so I'll leave it as it is (20% reflection). Goes better with the car.

One question: where's the "light softness" setting? Is this what's called "Shadow smoothing" in the Atmosphere editor? I couldn't find any setting with this name and this value range.
Or did you mean the "Softness quality" slider in the light editor? It's always disabled.

**
Edit:** found it. It's for whatever unknown reason NOT in the light editor but in the preview window on the right side. That was, I must admit, the very last place I would have searched for it.

Aargh...UI designers...Urge to kill someone...