[Towncar]

Tracing water leaks requires a bit of finesse, and patience.

" Holes in the trunk lid? ", No, there are no holes in the trunk lid.

If you're located in the rust belt, you can have holes develop just about anywhere.

Assuming the lid seats evenly & adjusted properly, & the seal is in good condition.. You'll need to remove all the carpets and start some garden hose testing to see if it's leaking from the top side. After you rule that out, wheel splash is next, etc.

BTW, what type of roof material do you have? Does the rear deck get wet too? Rear shelf around the spare tire?