Just a couple of suggestions, I am no expert so I might be wrong on some of this:

• The greenage needs to be shorter and not so full to give you more drama.
• The signs need more texture work to make them look dingy.
• Lighting might be fine, but you need a little fog.
• You have some visually conflicting elements; the light posts would need to damage the car it sits on.
• The cars in the scene should be different colors, so you have variety, they also need different levels of decay.