After looking for a proper solution to mount my iPhone in the smart roadster, I didn't find anything which fits my needs. So I going to do it by myself.
The Mount fits in the left air vent, it has to be disassembled for the right mounting. The model also includes a little hole in the baseplate, where the little spring from the air vent slide in. So it is possible to rotate the mount for your needs.
I've printed it with matte black PLA, works and looks like a charm.
Update v2:
The author marked this model as their own original creation.