Don't you have an E70 already? The F15 is pretty much an LCI-on-steroids from the E70, IMHO. New sheet-metal; same basic vehicle concept. Except for the PHEV 40e (which was revolutionary), F15 was a sensible evolution of the E70 which I believe came from the same production line, same people, same parts bins.
The E70/F15 issues are similar. I'd frankly be more worried about the individual unit than about the F15 line overall.
The recurring serious complaints in this forum are the A pillar sunroof drain clogging in some geographies and the V8 being inappropriate for years of grocery-getting. But, again, those are common complaints across a lot of BMW vehicle types.
Go CPO (Certified Pre Owned) if you can. Like others have said, the F15 is a very well-engineered vehicle. The folks at Spartanburg really know what they're doing, having assembled X5's since the E53 debuted in 1999.
As an original owner, I went 160,000 kms before I had issues with the controller arm. My mechanic says this is a common problem and I went longer than normal. He also recommends changing the oil more frequently and stay within the ll4 certification. It's a fun truck to drive! Good luck in your search.
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