As mentioned, check intercooler hose, the top is pretty common (already) to go on a D4, remove it to inspect, only takes a tiny split to cause excessive black smoke.
*No new common rail diesel will be smoke free, they are so emission controlled (choked) and so rarely worked, as in 600NM of torque to drive small children 15mins to school, again chokes up modern diesels.
*Most people really done need to be driving a turbo diesel powered anything.
*To be fair, just to go back on my words slightly, its not so much the emission requirements thats the big issue, its poor engineering to implement the requirements.