New owner: smoke from vents

Hi everyone,
I purchased my first Mercedes this morning. I bought a 1999 E-Class 270 T CDI (I'm in Germany, not sure if they have the same sort of model elsewhere). The car has 200,000 km and seemed in good shape when I purchased it. I noticed on the way home, when driving on the autobahn, at 160km/h smoke started coming through the driver's side AC vent. At lower speeds this did not occur. I pulled off to the side of the road and had my friend run the car while I looked at the engine. There was a bit of smoke coming off the rear of the engine, it looked white or gray...just a tiny amount. Since that happened, there has been a persistent smell of burned rubber coming from the car.

I'm new to Mercedes and I don't know much about cars to begin with. I'll be taking it to the shop on Monday, but I'd like an idea of what is going on so I can brace my wallet. Anyone have any idea what it could be?
Cheers!