TBF those 1.8ts providing you stick to the oil changes they wil be fine. I've had a couple of A3s , A4s in our workshop with as much as 240,00 miles on the clock with the 1.8t and run fine.
(Audi, VW engines tend to have carbon build up/sludge build up, not only down to city driving where it doesn't get warmed up but can form on cars that have had regular servicing.)
My advice would be to change the oil pick up pipe (strainer) because if it blocks it can then make the oil pump fail. You will hear the bottom end being very noisy before you see the oil pressure light.
That in itself will add miles to the engine life and should help when being mapped to create some healthy torque figures and give you that peice of mind.
Also the master tech was saying to me the other day that 1.8ts that were driven hard from new tending to have more hp and go better than ones that were just pottered around and probably had low mileage but tend to last longer - so buying one from a carefull lady owner with 20,000 on the clock may not be as great as it seems.
My 1.8T AGU is on 115k and running sweet.
