Glad to hear you bought an A4.
I own 3...all are solid cars.
The key is join an Audi forum (try Audizine...excellent), learn up on them and change the oil with synthetic regularly and keep the maintenance up to date.
My 2005 has 265,000 kms (youngest son), my 2006 has 345,000 kms (oldest son) and mine is a 2013 with 223,000 kms.
All are 6 speed manual Sline quattros with go-fast mods.
NONE have ever let me down.
A big plus with A4 turbos...you can have a ton of fun modding and grabbing a ton of extra fun HP with tuning.
Enjoy sir!