It's a losing battle. Married almost 40 years and the wife's vehicle has always been a trashcan. If we go somewhere in mine, I have to pickup her trash after we're done. I choose my battles carefully and this isn't one I'm willing to die on.Mercedes ML 350 (wife unit)
She was out of town so I took a trash can and emptied out the SUV of all the crap. I usually refuse to sit in her car since it's a rolling trash bin. Took it down to the $5 car wash to wash and use their vacuum to hit the rugs. Windows cleaned and plastics wiped down. Cleans up nice, but 5 days later is trashed again.