Britney's baby sis paints a pretty horrific picture of what's been happening in her home, claiming her Tesla vehicle is so quiet her cats don't hear it turn on or backing up ... and they end up going from 9 lives to zero.

Jamie spares us the gory details, thankfully, but says it's devastating and tragic for everyone involved. She also suggests it's happened several times, but doesn't say precisely how many felines paid the ultimate price.

She also pitches an idea to Elon on how to improve Teslas and save cat lives. No, JLS isn't an engineer, but she might be on to something here.

Now, Jamie does admit some "user error" is also at fault, which seems appropriate considering it's happened more than once. As you can see in the video, it's made for some difficult heart-to-hearts with her daughter.