In preparation for a drive back from Ashville to Knoxville (126 miles door to door), I charged to 160 miles of range. I figured 20% over would be good and it was late at night so I didn’t want to spend too long charging at a closed Sam's Club. I drove about 5 mph over. The route takes you over the Appalachian Mountains. It was about 30 degrees outside. These three factors ate up most of the 20% buffer.
At 30 miles remaining, a charge soon warning comes on. At 22 miles remaining, cruise control quits functioning. At about 12 miles remaining, power is reduced and the remaining percentage goes from a number to “low”. You can still maintain speed, but the accelerator behaves differently.