Strut; Front suspension nut and washer (engine compartment)

['10CamaroDude]

-Deleted-

[cdb95z28]

The gap is supposed to be there.
It's easy to overthink it, that is the way they engineered it. I suspect it:

-Is inexpensive. Simple is cheap. And it weighs less.
-Makes assembly super easy on the assembly line
-The entire upper mount allows for good dynamic caster and camber. Without a major redesign that offers more softness there would be a compromise of the caster/camber control.
-Provides an acceptable level of NHV (noise,harness,vibration) control. Most people accept it's a sport car not a Buick, but everyone has different tolerance levels. Try a set of solid mounted camber plates and you'll see how true solid mount is worse with the NHV.
-I believe that the upper strut mount was redesigned at some point early on in the Gen5 life. But the same overall design remains.

The banging may not necessarily be a result of the downward movement. Remember, when the wheel travels down in a hole, it hits hard on it's way up too. All within milliseconds.

Something like a change of tire brand/wheels can alter the engineered chassis dynamics, creating uncontrolled NHV.

Here's a pic of my '14 before I installed camber plates. You can see the gap.

[CamaroBarb]

If you turn the steering wheel to either lock you will see why the gap is there. The strut angle changes in such a way that the space is needed so it doesn't bind.