Did this test last year to see if Blender3D can be use to render anime style cityscape scene. The result is quite good to be use a starting point for paint over. I believe if more time are spend on the 3d side, we can skip the 2D paint over process.
It render fast even though it look like quite "heavy" or "a lot" to render. This is because the building are just low poly with image texture. Image below show thge lowpoly building in viewport view and GLSL render. It look a bit like simcity in Isometric view.
ArtworkThis is a version with minor touch up, the cloud are added in with photoshop. The rest are all straight from render using Blender3D internal render.
More renders with different colours on sun lamp and hemi lamp.
More info on how to import openstreetmap vector data into Blender3D can be view increativeshrimp tutorial.
ReferenceDeviantArt Blender3D CityScape
DeviantArt Blender3D CityScape Evening and Night
DeviantArt Blender3D Nightscape
Pixiv Blender3D Nightscape
Pixiv Blender3D CityScape