It's hard to measure battery
It's hard to measure battery range, especially without knowing what the reserve is that the Bolt has built in.
Most electric cars have eg: a 120 or 300 mile range, plus an additional 10% that isn't user accessible.
Tesla unleashed that during a hurricane state of emergency in Florida through a software update.
Nissan has a similar 3 to 5% of 'hidden range', that should give you pretty consistent range the first 100k miles, at which you can still say you have 95% of factory range, not accounting for a few percent of the reserve cells that have been swapped out through the software, with the bad cells.
The battery degradation curve is made to look as straight and linear as possible, all until a certain point (usually ~80%), after which the remaining cells will rapidly discharge and lose power.
All it takes is one time sitting still for a few months.