Hey another Aussie Artist, welcome!
Very nice work on the mazda, the styling looks really cool, just a few simple things to look out for so that all the parts fit the environment.
Adding to what szaba18 said.
-The inside of the tyres need to be a bit darker to blend in with the shadow.
-The lines of the rail line should be faintly reflected on the rear bumper and skirt.
-Background of the image is quite warm (orangey), where the mazda's white paint is rather blue. You could run a photo filter so that the car and BG blends in a bit more.
Anywho, nice work on the car, Hope to see more from you in the future.
Cheers,
J