Very cool idea francescof. I Didn't expect to see a massive engine from the top of a classic skyline.
But:
-The engine and window frames are too blue and need a bit on contrast as they look flat.
-The car seems to be a bit too bright, compare to the bright background.
massive blasphemy to one side its a nice pic. I'd be tempted to put a little more contrast on the engine and maybe re touch the areas you've changed to convert it to LHD