Here's one for you, and I would never have guessed it.
My daughter bought a Japanese brand car brand-new in the last year. Got water behind the driver's seat. Shop couldn't find it the first time. Eventually was found to be the trunk weatherstripping was incorrectly installed at the factory and let water pool at the lowest point it could follow - behind the driver's seat. She got another vehicle from the dealer in the end. Go look at the trunk, just a suggestion.
My daughter bought a Japanese brand car brand-new in the last year. Got water behind the driver's seat. Shop couldn't find it the first time. Eventually was found to be the trunk weatherstripping was incorrectly installed at the factory and let water pool at the lowest point it could follow - behind the driver's seat. She got another vehicle from the dealer in the end. Go look at the trunk, just a suggestion.