I have noticed smoke coming from exhaust manifold area especially on start. BMW X Series Forum – Technical Talk on the E53, E70, E71, E72, E83,. can also break and leak diesel which ends up on the exhaust manifold.
Go up under the hood with a light and a mirror and don't see anything but I'm thinking exhaust manifold leak. Maybe that little donut looking .
BMW New Replacement Cast Iron Exhaust Manifold With Gaskets Nuts. Developing cracks or slits in the manifold causing exhaust gas leaks and the. .. Tube EGR Valve Delete Bypass kit for BMW 3 E46 5 E39 7 E38 E65 X5 E53 X3 E83.