This proves my point.
Here, it lists the second generation FLIRs on the SEPv2 changes, not on the SEPv3 ones, as you listed above, for example:
Above, you listed 15 features, while this screenshot lists 7 features. That means you initially did indeed list features from all SEP iterations respect to base A2 retroactively, while this second list specifically addresses SEPv3 changes respect to SEPv2.
The reason why APU is listed on SEPv3 is that it’s a new model compared to SEP/SEPv2’s, indeed. But one that would reinforce my point regarding weight, if anything: I don’t know how much SEP/SEPv2’s APU weights, but SEPv3’s APU weights 190 mere kg. 10kW Low Profile Auxiliary Power Unit (APU) for M1A2 Abrams SEPv3
If the APU, one of the heaviest new additions, weights 190 kg, you can imagine the rest of the electronic/electric improvements won’t surpass 4 tons, which is exactly what was saved as well with the weight-saving measures.
Then you have 5 extra tons left. 5 extra tons that can’t be explained without attributing them to further armor improvements.
I insist:
M1A2: 62 tons
M1A2 SEP: 62.2 tons (+200 kg)
M1A2 SEPv2: 64 tons (+2,200 kg vs A2, + 1,800 kg vs SEP)
M1A2 SEPv3: 67 tons (+5,000 kg vs A2, + 3,000 kg vs SEPv2)
All of this when there’s also -4,000 kg worth of weight-saving measures between A2 and SEPv3; and even in spite of these, the tank got 5,000 kg heavier.
It is impossible and nonsensical to suggest that the tank got 9,000 kg worth of extra/improved electronics and electric systems when even the heaviest element, the APU, weighs 190 mere kg. Accounting for all of the electric and electronic upgrades, as well as all of the quality of life improvements, it is impossible that these add more than 4,000 kg.
Now you got 5,000 extra kg that can only be explained via additional armor.
Analysing just the weights and taking into account all the new features and the weight-saving measures, I would dare to speculate:
SEP: turret armor improvements. Weight saving measures + additional turret armor weight + APU = 200 extra kg.
SEPv2: SEP’s turret armor improvements + first hull armor improvements. Further weight saving measures + lots of additional armor + quality of life improvements = 1,800 extra kg, a substantial increase vs SEP.
SEPv3: even further turret and hull armor improvements. Minimal improvements + substantial armor improvements = +3,000 extra kg compared to SEPv2. An incredible armor upgrade by this point can not be denied.