and I had mine done at 75K to make sure I kept my extended warranty in place.
2013 A8L 3.0T Phantom Black Pearl Effect with Velvet Beige Interior. Sport Design Package, Driver Assistance Package, Panorama, LEDs, Cold Weather Package.
SOLD - 2008 A8L Northern Blue Pearl Effect with Linen Beige Interior. 19" wheels, Premium Package, Seat Vent and Massage, Driver Assist Pkg, Solar, security glass, door closers and Rear Climate.
SOLD - 2004 A8L Light Silver Metallic with Blue Interior. 19" wheels, convenience package, cold weather package, parktronic, XM, AMI and Bluetooth.
Audis Before A8:
2001 A6 2.7T Blue over Black
1998 A6 2.8 Silver over Black
used to be 105,000 miles. Belts have been around since the first Fox/VW motor in a four banger from about 72 (or Rabbit, etc. before that) and the 5 cylinder 5000 from 1978, so this isn't new. Having owned 'em for the whole period, the actual reported incidents of Audi belt failure are quite low. Hondas are known as having far more for example. In Audi drivetrains I would say the tranny and CV boots are more the weak spots traditionally. Having done belts on Audi 5's, 6's and 8's, the 8 belt is in turn beefier, and actually a lot of the old high valvetrain resistance you find on an older motor has been cut down a lot in search of performance, higher revs and economy as well.
For myself, if my car were a long distance/vacation type traveler I would do it by the time I thought there was any real risk of issues w/ related parts--pulleys, water pump,theromstat serp. belt, etc. And on the motor, if the water pump outright locks up (really very rare; they usually leak way earlier) it's all over for the belt and then motor. I would call that increased risk areas maybe 100K or 7-8 years traditionally, and again probably most focused on the water part. Gets back to the old 105K interval.
If you want to be cynical by the way, notice the interval is outside any extended service offering they now sell, but inside the CPO warranty window where they would eat a new motor if the belt failed and it wasn't a service interval item. Or, if you look at Honda, they paid some $$ as I recall for Prelude and other engine repairs where the belt was in question.
Some here have nicknamed me "Miser Bally" as I refused to do the timing belt at 75K miles. I'm at 116K IIRC and recently I pulled off the covers and inspected the belt. It still looks fine. I know I'm playing with fire.
In case I haven't posted it, My 2001 Beetle turbo with 1.8L engine has a 105k interval. At 94K the belt failed-actually the idler pulley started squeaking for a week or two but not very bad so I kept driving. Well, eventually it failed so the valves (all of them) kissed the pistons. It was a $5k repair. VW ate it since the recommended interval was not reached.
I know that on my 4.2L engine, it will be a *bit* costlier and I'll have no recourse. I'm going for 150k miles but in case the water pump starts to leak, that will cause me to do it. We'll see if I try to tacle it or pay the big bucks. I priced the tools from Zelenda,; about $500.00 Figure $600 for the parts from a dealer and them lots of my time. Fortunately, I have spare cars.
The kit from Blau parts is about $500 and they offer tool rental for $50 but some have said that their parts are not as good as OEM so I won't take a chance. Plus I hate time limits that come with tool rentals.
I had my 2004 in for the 95K service today. The dealer made the comment "you should change the timing belt at 105,000 if you haven't already." (I already had it done at 85K.) So obviously he was comfortable with going up to the old 105K number.
Your lucky to get to 75k without thermostat failure.
You can't replace thermostat without removing timing belt!! Independent shop who does all my work had replaced thermostat(stuck shut), water pump and belt service at 75k. Now at 125k thermostat failed and water pump bearing also bad. Full belt service again! $1500.00
Funny story....t-stat went last summer when under warranty. Figured that while they were in there they could quote me on the t-belt job. I cannot remember the exact number but do remember that it was a stupid number. When I tried to negotiate it down since they were already in there for the t-stst they basically declined. Brillant business decision.