I have a 1999 A8 recently bought. there is a button on the driver side just below the trunk open button. Can anyone tell me what is it for? Thanks

 

Ejection seat. Duhhhh!!!!!

 

It's to turn the sensors inside the car on and off for the alarm. Try a search and you will find about a thousand posts.

 

Yeah! What Cary12 said, HansBlix's answer was the same one I gave, somewhere around the 750th time the question was asked

An ejection seat WOULD be a nice option, but ONLY on an Aston Martin, I think...

 

It lets you sut off the interior sensor for the alarm, if you have pets or something this keeps it from going off everytime they move. It is aslo nice if you leave the sunroof open to push that button, the wind sets off mine.

 

Or if you have to have your car flatbedded you can then lock the car and not have the alarm sounding off.

 

Even better, if, for some reason, you want to go take a nap in your car while it's in teh company parking garage, you can, without the alarm going off and scaring the **** outta you (true story, it DID happen to me. and, YES, I wet myself, but only a little)