* Audi's official website: The manufacturer's website often provides detailed specifications for their vehicles.
* Car review websites: Websites like Edmunds, Kelley Blue Book, and Car and Driver usually have detailed information on vehicle dimensions, including rear shoulder room.
* Owner's manual: If you have access to the 2007 Audi A6 owner's manual, it should include specifications.
You can also search online for "2007 Audi A6 rear shoulder room" to see if there are any readily available results.