The second or third owners talk about engine swaps.
At least with the older models...
A friend is getting an M3 engine swapped into his E46 sedan (like mine, already with 6MT) right now. I helped my brother rebuild his engine earlier this year...nothing terribly exotic about that process.
I wish I could buy, store, and preserve an E46 and E39 to use in the future...I'm not interested in iDrive and similar silly stuff. I just want a great driving experience in a vehicle that has an engine, transmission, and differential in order from front to back as God intended! And no super invasive do-dads that go bad after 100k miles. /yells at cloud