Rusty spots in the lower left corner of the rear window space. If it is raining, water collects on the glass in this corner and stays there until it dries. In this particular car it is a surprise that the corner has not leaked and the water thus has not affected the corner of the parcel shelf. Even cars in much better condition suffer from this.
The left fuel filler opening is visible to the left of the picture. The parcel shelf is visible in the right half of the picture.