Search didn't find much info for the A8 and it seems every manufacturer is different in how they put those damned things on. Denatured alcohol works on a Porsche but it's been a while since I did it on a Audi.
What works best to dissolve or remove them on a A8, '06 in my case...
First I tried picking at it (upper right corner of where sticker was--the material is a tiny bit rougher but you have to be staring right at it). Just couldn't get it--no more than about 1/4 square inch at a time. Then tried heat. No go.
Solution: liberal application of garden variety isopropyl rubbing alcohol--I used the high test/100% stuff. I put it on with a rag soaked in it and let it get into the alcantara material at the edge of the sticker and also tried to soak it into the sticker face each time. I usually went about a minute from application to peel attempt. More patience--maybe a five minute full sticker soak might have worked best. I could sometimes get a square inch or more, and now it peeled evenly most of the time without feeling like I might mess up the fabric. The sticker material was nasty, often resticking to my fingers.
Once I removed it, I simply opened sunroof and windows and let it air dry overnight. Liquid darkens the alcantara a bit when wet, but it was obvious right away it wasn't stripping any color/dye and no obvious adhesive was left behind so I figured it would dry fine. I can confirm there is no appearance of any liquid stain whatsoever. Medicine smell was completely gone overnight.
If you look carefully you can just see the sticker outline. I peeled it about a week ago, the car is a 2006 with a build date of May 2005 and a delivery date of August 2005, so it has about two years of general upholstery fade. In practice you don't see the sticker border mark in everyday use. I took this picture at 8MB originally with a flash on a Canon SLR.
Now that I got the general technique down, I would say it is about 30-45 minutes per sticker to do a reasonable job.
I figured I could always apply a new sticker if I had to hide a problem...
as long as it didn't stain or snag the fabric big time. It worked out fine.
I also took off the big yellow doorjamb stickers that seem like way overkill--the French translation for Canada makes it doubly visually painful, especially on a black exterior car. They are an easy removal and come off in one piece. Then I noticed the car also has smaller and more tasteful silver stickers in the doorjamb/fender area that have much more a factory look. I left those be.
Thanks to MP4.2+6.0 for the sticker removal tips. It's worked great so far.
I did the two long thin stickers on the non-mirror sides of both visors using 70% isopropyl alcohol (only percentage I had) and cotton ***** (about 7 or 8 per sticker). I used a insignificant amount of the isoproply in the process.
At certain angles, you can make out a very slight ghosting in the texture of the alcantara at the edges of where the stickers used to be. I used a suede brush to rub the uncovered fabric a few times after the visors dried and that might of helped but I don't think it is necessary.
My alcantara is amaretto as well. There is no discoloration that I can perceive. My girlfriend agrees and said that it looked much better without the stickers.
Tomorrow, I will try for the two big rectangular ones on mirror side of both visors. I will take pics after it's all done and try to remember to take some during the removal as well.
Current: 2003 BMW 540iA Msport (e39) until my Tesla Model S is built.
1988 BMW 325 (e30 SuperETA), soon to be registered as California classic vehicle.
2007 A8L W12 (brlnt black ext, black/amaretto int. W12 options: sprt pckg 20's, B&O sound, AMI retrofit, adaptive cruise, solar sunroof, full leather upgrade, four power seat config., US front bumper markers delete, visor airbag stickers delete.)
2004 A8L 4.2 (brlnt black ext, black int. Options: premium package, cold weather package, front head/vent/massage, 4 zone climate, rear lumbar)
1997 A4 1.8T quattro sedan (black ext, black/grey int, modestly lowered)