As with any image, the re-touching process should only be done to the point of balance and vision, if the car was in the image, then it should be in the image, I agree with the Tourist, if you want one without the car in the image, go back and get it, as much as people gripe about PS, you can accomplish the same amount of mess in the re-touching with a traditional means as you can with a computer.

That is part of the beauty of photography, not the shot you have already taken, but the next adventure to get the new shot..