Its hard to tell where the truth lies on AVS.....i take the line that it cannot be desirable for a performance car (certainly S class) to de driven up to 19k miles on the same oil.......
.......However given that most customers probably do not drive their audis day in day out in a hard fashion, then I see no reason in principle why the engine self diagnosing when it thinks the oil needs replacing cannot be done successfully as long as the technology functions how it should.
I certainly have faith in the VAG engineer's and the likes of Castrol's ability to be able to work together to produce an oil and sensing arrangement that accomodates the different ways in which use of an engine can affect the ability of the oil to do its job. I do not see it necessarily as a money saving feature, but if the tech works like it should, then your average (non car technology literate) audi driver can have faith that they are replacing oil when it DOES need replacing, not slavishly at 10k intervals.
My understanding is that AVS was introduced (on the A3 8L) at the start of MY01 ie, Aug/Sept 2000 at least for petrol engined A3s...certainly 1.9PD units didn't follow until MY02
My understanding of the tech is as follows.
There was an excellent article in audi driver magazine back in 2002 about exactly how the variable servicing setup worked. I haven't got the mag with me at the mo...but it goes along the lines of monitoring the frequency, duration, engine temps of your usage and it also monitors the state of the oil. The clever bit with this is how it uses an heated element in the engine which if i recall correctly is heated to a set temp and then left to cool while monitoring it's rate of heat loss. In the ECU is a map of how quickly the element should dissipate its heat, ie, rate of change....against a given oil viscosity. Obviouisly as oil ages it breaks down and this therefore affects its ability to dissipate heat....when the oil has aged to the extent that the oil engineers believe its no longer doing a sufficient job than the map is designed to flag this up along with the other parameters that contribute towards an overall view of how hard the oil's life has been.
So in principle, i would say i'm for AVS...However if i want a PERFORMANCE car like an S3, i just prefer to sleep safer at night knowing that replacing the oil more often will obviously be beneficial to the long term health of a hard used engine. There are tales around of AVS cars whose oil comes out as thick sludge come 19k miles.....i personally have not witnessed this and if the tech does work like it should, I see no reason why it should be like sludge....certainly Foolish does not agree with those who talk about sludge like AVS cars.....not that i'm saying Foolish is an authority , but since he works as an Audi Tech his opinion certainly does carry some weight for me.
Just all IMHO, gents