My X5d - 2011 model, June 2010 build.
A few times, either under hard acceleration (3,500+ rpm) or first start for the day inside the garage, I got the diesel smell inside the cabin. Since it was a rare occurrence I thought I will address it at the next service visit. I did not experience this smell while driving on the highway.
Emailed my SA about this, he was super concerned about this as he felt this could impact safety - cabin getting flooded with foul air. Within 20 minutes of arriving at the dealership, his tech confirmed I had a cracked EGR cooler. Fortunately the Dealer had a spare on hand and the work was completed in a couple of hours. (Dealer - BMW Concord, California)
Attaching the service report for reference.
Separate topic - just learned we are entitled to one set of wiper blades (front and back) every 12 months under the BMW maintenance program . . . but you have to ask for it, it does not get replaced automatically.
My "charge air temp sensor" was replaced last May after it failed and tripped the check engine light. Now there is a bulletin out asking the techs to replace this sensor regardless of whether the sensor failed or not . . . mine got replaced again - yes with the exact same part.