[smovva]

Took my 2011 X3 (Build date 05/2011) with 20K miles into service this week as the car has a couple of problems:

1. Very jerky acceleration. My loaner 2013 X3 is silky smooth by comparison.
2. A few times a week when coasting to a stop or turning, car would drop RPM's like its misfiring and almost stall.
3. Rattling noise from undercarriage. Sounds like heat shield or something rattling in exhaust. My loaner 2013 X3 has no such noise at all.

For #1 & #2 I assumed they would update software like they did last year in May 2012 and all would be well. For #3 I assumed they would tighten some heat shield or exhaust components and all would be well.

SA called me now to say the jerkiness is due to a bad transfer case they are replacing under warranty next week after part arrives.

I am curious if you have heard of a transfer case causing jerky acceleration or perhaps even being responsible for the other symptoms #2 and #3 as well. The SA did not indicate what they found to be the issue with #2 or #3 yet so I am hoping this replacement may fix the other issues as well. BTW, what exactly does the "Transfer Case" do?

Thanks for any insights!