That's my all time favourite ghost pic. Then someone pointed out that the dead mother's white neck scarf seems to overlap the edge of the driver's window frame which is a bit suspect.
And I've read that one of the investigators of this photo claimed that the inside of the window frames on this model car had a 'velvet' lining, which would give a 'blurry' or 'hazy' edging effect to whatever is photographed behind it. It's not the clearest of photos, and it's from 1959 so probably an old type camera, which doesn't help the clarity.
The thing with this photo is also that she is blocking out the back window, so she's definitely there.
Jim and Mabel Chinnery also appeared in a tv show, seemed they truly could not understand this photo themselves.
And it's my favorite ghost photo as well!