I've used regular (85 here at altitude - equivalent to 87 at sea level) in all of my BMW gassers ever since a client who drove BMW's told me he'd switched to regular with no discernable effects. The N52 in my wife's E83 has the highest compression ratio at 10.7:1 of the engines we've had, and I've observed no negative effects from running regular. The M54 is barely a high compression engine at 10.2:1. Your N63 is in between at 10.5:1.

If you drive hard, it might be a different story, but we tend to drive pretty conservatively. As always,... YMMV.

AM.

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E70 2010 3.0 M57 AT Titanium Silver with Black Leather
E53 2004 3.0 M54 AT Toledo Blue with Gray Leather
E83 2008 3.0 N52 AT Silver Gray Metallic with Black Vinyl
E46 1999 2.8 M52TU 5MT Black with Tan Leather 250K+ miles (Sold, but not forgotten)