you've totally ruined it. it seems that some of the reflections are a bit out of perspective. the back is too dark, and the front is almost too bright to match the rest of the car. if the skies were that dark, and you're using a 1/100th shutter speed for example,
shouldn't the skies somehow reflect on the front windows too ? i could be wrong, but it's just what i see. one thing i do like about it is the dirty looks on the doorline and near the airvent of the car. makes it look dirty. just wish the skies were a little bit less noisy and a bit brighter. to be honest, you should have just kept the original, or blurred the sky a little bit to kill the noise levels, or did a black and white conversion. then maybe the hdr could of worked out better.