So I was looking on Fuelly at one of my vehicles, and it was telling me my average fuel economy was poor. So I was scanning through my fuel ups, and found it has no fuel records before April 2014.
This is a 1993 300zx Twin Turbo that I have owned since May 2010. All records were entered into Acar, and in fact all my maintenance entries are still there. But all the fueling from 2010 to May 2014 has just vanished.