My older car had some annoying leaks that were from loose weather stripping and a sagging headliner frame on the inside roof of the car. It was a trial and effort to push them back in place and reglue the stripping but I eventually got the leaks to stop. I even did a pretty nifty job of stapling the sagging headliner fabric back up.
Cars should be completley weather tight and their interiors dry no matter how bad the rain. I'll never have a sunroof or a convertible for that reason, too many complaints about leaks.