The vehicle is only polled every minute if it is actively driving or charging (based on the prior minute's vehicle states). If the car was previously charging and it now is "Completed" or otherwise the cord is unplugged, that update gets logged. The following minute, since the previous update was a conclusion, it will stop polling the update for 15 minutes (or 60 minutes if on the normal sleep mode).
During this time, if "Restful" sleep is toggled, when the car falls asleep (deep sleep) during those 15 minutes, if the vehicle's state returns as "asleep" (we can do this call without waking the vehicle up) then polling is paused indefinitely
until the state changes back to "online", strictly due to the owner interacting with the vehicle in which polling occurs again. More information on this can be found on our
Help Area.
Also, here's a screenshot of my own vehicle's sleep settings!