Still this thread is on, so I put some thoughts also in ;-)

Depending how far you would like to go in your scene following comments:
=> it seems the sizes of the cars dont match with the building size, a normal floor height of a high-rise building has approximate 3.8 to 4.5 m height. If the left building is for example a leftover of an office building the cars seem to big
=> I would reduce the quantity of broken stones / asphalt on the road and add more "normal" garbage instead
=> in a normal case such buildings have company names on it, shops are in the downside, there are entrance areas
=> the structure of the street doesn't look real, a normal walkway in a big city has different areas of paving for example, entrance areas to the park house or backyard parking, posts, the center of the road might had trees (depending what happened in your apocalyptic incident ;-), anyway some "green" or now grey areas with plants or trees
=> street names, posters at the wall, maybe even some newspapers stuck to the walls with the bad news!!!
=> its not really visible if you still have some glass at the facades or in the windows
=> the rusting car is very corroded comparing to the other cars like the police car which seems is still shiny.....

Yes the sky is too blue for the light, try to use overcast weather instead.

Hope you continue to improve your scene. Excited to see the final product.

By the way, what happened in the Apocalypse ???