So the first time this happened, I charged the battery back up overnight and the car started. 2 months later, same thing, battery is down to 8 volts for no apparent reason. I pulled it into the driveway yesterday, washed it, and put it back in the garage. I did not notice the lights remaining on, but that is the only thing I can think of that would drain the battery down. Now sitting in the garage with a charger on it and the interior lights won't go out....I called the dealer and they were happy to book a service appointment, but that would suggest that the car COULD start off an 8V battery. Anyone else out there experience a mysterious "draw down" on the battery? 7800 miles.