* Your car's owner's manual: It should list the rear track along with other vehicle specifications.
* Audi's official website: Look for the 2014 A6 model page and search for specifications.
* A reputable automotive website: Websites like Edmunds, Car and Driver, or Kelley Blue Book usually have detailed specifications for different vehicles.
* A mechanic or automotive specialist: They can look up this information for you or measure it directly.
Please note that the rear track might vary depending on the trim level and wheel size of the specific 2014 Audi A6 model you have.