I've owned the M4 since 2015 October. I can back @edyvw that this engine originally was designed around LL01, not FE because when I first got the car, the dealership would only change w/ with LL01 0w40 or LL01 5w30. 2 years after that they allowed for LL01-FE 0w30, and it started appearing in the new car manuals.
I feel all manufactures are moving towards the thinnest oil possible for the recommended drain period for CAFE / mpg reasons. I don't see how my car can call for LL01 initially (3.5 HTHS minimum?) and now the recommended version is a FE oil. Will there be any difference to the car in 100k miles? Probably not - but as an enthusiasts and someone that beats the [censored] out of the car I'll just stick to the original manufacturer recommended LL01.
All N-series engines (4,6,8,12 cylinder) and their S-derivatives (excl S62,S65) are spec'd for LL01 FE or the mid-saps equivalent LL12FE. Agree BMW has been all over the place and you'd think that they would offer a "track use" recommendation.
I doubt that BMW, VW or any other mfcr just chooses any, off the shelf FE oil, slaps their approval on it and says, "now go drive your M or GTi at 65mph max.
Within the context of historically thicker euro oils, ya LL01FE is thinner but it's no thinner than say regular Mobil 1 5w30. BMW spec'd a 10w60 for a certain family of M-engines and some owners routinely ran M1 0w40 w/out a problem for street driving.
