Your ambience
should not be set to 0. Shadows cast in well-lit settings are not completely black.
Use
entities rather than segments for buildings unaccessable to the player to rid your level out any unseen polygons.
You can create a few unaccessable/blocked off areas on the outskirts of your map still visible to the player to make it seem as though the city goes on behind the areas the player cannot get to.
Use planes with a simple building face texture on them in the background of your city to create the illusion of a more cluttered city environment, without adding many extra polygons.
Using low-poly "trash" to clutter your streets is a great way to break up the repetitveness without adding a lot of unneeded polygons. The newspapers in my signature, for example; use between 2-8 polygons a piece. Scatter 100 of them around the street, and it will add less than 1,000 polys to your level.
To save polygons, use large static geometry such as delivery trucks, buses, dumpsters, etc to clutter up empty city spaces rather than dozens of small entities.
Use streetlights, stop signs, post boxes, telephone posts and wires, but use them sparingly and spaced well enough apart to conserve polys.
Kravenwolf
