I agree with what lyonsroar said about the exposure...
If the cars had been properly exposed you could have applied some soft light gradients to the background to darken them but the cars well lit. I would have also made a new layer and painted black of the windows and changed the blending mode to soft light and played with the transparency to give the windows a tinted look. Also I would have cloned out the ducks...not really sure what they are for...