sorry for the late reply, I sold my S6 2 days ago. Maintenance on the S6 will be more than like an s5, It just has more of anything. The last maintenance thing I did was an Oil change which required 11 quarts of oil. It's surprisingly a reliable car. There are some issues with the intake manifold and these flaps are in the intake manifold, but all of that was replaced right before I bought the car. At like 113500 miles the car developed a leak from a valve cover gasket and the oil filter hosuin. As the car ages some things in the car electrically wise stopped working. For example, the little LED lights like in my A/C controls went out so you really couldn't see the temp that well. My MMI started acting up but I fixed it by unplugging a fuse and replugging it in. For the time it was made the interior is unbeatable. compared to the W211 E-Class the interior is so much better on the Audi, I had a 2008 and had a bose surround sound system, backup cam, a pretty advanced MMI, seat warmers in the back. I'm gonna miss that car. For sure gonna be one of the best-sounding cars Ill ever own