do you have a sunroof in yours? they have a big issue with the hoses from the sunroof drain coming off and leaking.i've got a 2005 g6 gt and recently it started leaking on the driver side door when it rains or when i take it thru a car wash i searched customer reviews with this particular year and model and it seems to be a common problem but simply replacing the weather stripping didnt work for any of them. i guess theres not too much to worry about since its winter now here in canada but if you guys got any ideas i'd appreciate it
that's the most probable cause