Where is the ATF fill plug located on an 8-speed automatic, 2012 A4?

 

If it's like the others ones, it's in the bottom up in a recess (couple of inches at least) in the pan next to the drain plug. You have to fill it up till it runs out (yeah, it can get messy) then fire the thing up, letting it pull the fluid out of the pan into the pump. While it's still running refill the pan till it starts to spill out. Still while running, shift the car through all of the gears to push fluid through all of the systems. (Generally this is done with the car jacked up level with all 4 tires off the ground). Still while leaving the engine running, top off the fluid till it starts to spill out. Install the fill plug. THEN, turn off the engine. When the engine is turned off, excess fluid will drain back in to the pan so if you leave the plug out, it will overflow. This method, while it seems to be more complicated than it needs to be, insures that a certain amount of fluid is always in the pan when running to insure proper operation.