VW Passat B6 TDI Blown Turbo

This is not my car as I would’ve had this fixed long ago. Company car from my uncle. Has been driving like this for about a month now that I know of, possibly longer. I took it for a test drive, and it just lacks power big time. Basically driving without the turbo. Also puffs out a lil black smoke sometimes. We recently took the car through the mountains in Bavaria and Austria also, and I’d have to say we were lucky we never broke down. It still reaches 210 kmh which is surprising also with a blown turbo, a