A Moto G 2015 has only 8GB storage.
Even mid-range devices sold today only come with 8GB storage, of which 6GB are used by the OS.
The Moto G 2013/2014/2015
https://www.amazon.com/Motorola-Moto-3rd-Generation-Unlocked...
> And what price range are you using to define mid-range?
$200-$250
> Is there even a low-range (lower than 8 GB) if 8 GB seems to be the absolute minimum, since the OS won't even fit on something smaller?
See above.
The only Moto G model that doesn’t offer 8GB anymore is the 2017 edition.
A Moto G 2015 has only 8GB storage.
Even mid-range devices sold today only come with 8GB storage, of which 6GB are used by the OS.