I couldnt figure it out a couple weeks ago when I ran out of gas near a busy intersection (never happen again that's for sure). There should be a way though. Would've helped me as my car was near a parking lot and could've been backed into it if I could've gotten it to neutral. Instead I had to sit and wait with a cop behind me until we got help for the gas.
-------------------------------------

The A8 shifter is all electronic and no way to get to neutral using the shifter with the engine off.

But there is a way to do it in an emergency when it is outlined in your Owners Manual.

Basically next to the shifter you pry up the coin holder and you will see the emergency neutral strap, move locking tab to the right to unlock then pull up on the strap and the trans will go to neutral.

Caution: If you just pull up without unlocking it you can bend the tab and the most important thing is once you pull the strap, the car will roll so make sure your parking brake is set before doing this!

Again, this system is designed for an emergency like getting pushed or towed and is not designed to be used every day.

Check your manual under What to do in case of Emergency for more info.