Greetings,
My brother has left his '98 A8 in my driveway and I would like to add some
gas to it but can't find the button to open gas cap door. No owners manual available either
...possibly that is on-line some where ? Thanks Syd

 

As you stand, looking at the gas-cap door, push on the r/h side of the door, near to the gap, and it'll flip open. No *secret* button to be pushed. Oh, and, make sure the car is unlocked as locking the doors locks the gas-cap *door*, too.

 

Hey while your walking around filling up peoples cars feel free to stop by my place and fill mine up too

 

Don't forget to leave your doors unlocked, so he can get at your gas cap...

 

Mission accomplished.....I thought it might have been in the glove box which I was not able to
figure out either. They are returning from the airport and the tank was nearly on empty.
...Unfortunately at today's gas prices my free fill up policy has been curtailed..but
the $20 I did add was worth it just to hear that lovely engine sing.
Thanks for the quick assistance....Syd.