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All the same. If anything, the small roof spoiler #2 may make like .3% difference, essentially insignificant. Keep in mind that air is being significantly affected out to 1 meter, so a 10cm add on will do little to change the gross air flow. People have a misconception that only the air within a few centimeters of the car is important and such is not the case.
Picture #3 would do nothing, guaranteed. If you want to make a significant change, you would really need to make a large extension on your car like this which you say is not possible.
Modern cars have been significantly improved in their roof shapes, particularly where the top of the front windscreen meets the roof, this radius has gotten considerably larger, as well the roof shapes in general are much more curved on hatch backs, by doing this it eliminates the need for a spoiler.
On some cars, the angle of the rear hatch and how the transition was made really created a huge lift, for these a 10cm spoiler was a significant change by not allowing the air to try and attach at all.
The angle break on the car illustrated is too much for the air to remain attached, so the spoiler will not help much.
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