e-loop (requires iStop), however, istop does not require e-loop. The systems are related - charge battery, maintain electricals, energy 'harvesting' etc - both can be displayed in real time regarding the status on the connect screen.
e-loop is more high end tech, and i-stop is mid-range. Both require software for the vehicle to monitor/diagnose and engage the various systems/components (the actual parts associated).
Well this is how it works on the models here in South Africa.
So no, a software upgrade won't add on the feature. I think mazda has some explanations regarding how the pistons assume a set position when i-stop is in use, whenever you come to a stand still.
Over here, all models that come with a MZDconnect screen (with and without Navigation) have i-stop, but only the automatic top of the range (individual and individual plus) come with e-loop. It's not optional extra, its standard feature.
Personally, I prefer manual driving, so i-stop is all I have on my Dynamic. I don't see e-loop as much benefit, unless you like that sort of 'green' technology etc, the wife's 2 series has it... as I said doesn't do much.
2016 Cx-3, 2.0L petrol, manual transmission. South Africa.