This part is listed by BMW as BMW part number 51718054281 (51 71 8 054 281) and is described as Genuine BMW Deflector Lip, Left, for the F80 M3 sedan, F82 M4 coupe, and F83 M4 convertible.
This lower plastic under panel piece integrates into the belly pan of the F8X M3/M4 on the left side (Driver's side on on US spec LHD models) and can easily get scraped, damaged, cracked, and broken. If the left side of your belly pan is drooping down, it may lead you to this plastic underpanel extension piece. This is used on all F80, F82, and F83 model M3 and M4, including model years 2015, 2016, 2017, 2018, 2019 and 2020.
For full BMW fitment information or for assistance from one of our BMW experts, we recommend calling us at 877-639-9648.
BMW Fitments:
3 Series
F80 (2015-2018) > M3 (2015-2018)
4 Series
F82 / F83 (2015-2020) > M4 (2015-2020)
F82 / F83 (2015-2020) > M4 GTS