There we have it, another Mythbusters Mybb Episode.
Ok so turbos are the new diesel tractor engine, never break and any backyard mechanic will have the spares readily avail at the local Midas and be able to cobble it all back together. In business!
If any part on your elegant new old 2hnd Audi is from the VW/Audi shared parts basket you are going to win because everyone knows an Audi is way better than a polo and why go 2nd best if the maintenance costs are the same. If anything Audi/model specific breaks just ignore it because it's not important/you can't afford it anyway.
Any well maintained Audi or Mercedes-Benz at 150000km is just amazing value for money, engine barely run in, let's just hope the seller/salesman was 100% honest and upfront about the only going on long journeys/how easy they were on the car/the awesome engine oil they used because we all know how things can quite easily turn out to be rather the opposite when buying used goods.
But don't worry and don't forget the obligatory R60k gearbox/cylinderhead etc slush fund just in case it all goes pear shaped, that'll be there gathering compound interest till that fateful day, money in the bank so they say!
So the wise money is on a higher mileage Audi or Merc, around 150000km is just awesome, must have a turbo and preferably some kind of tronic, ie tiptronic, multitronic etc, hassle free low cost motoring ftw.
Op sorry for the derail, can't let pearls of wisdom like this not be exalted.