From Google AI:
On the BMW B58 engine, the starter is [* located on the passenger side (RH) of the engine bay,] mounted low down on the transmission bell housing. It is accessed from underneath the car by removing the large aluminum splash shield/underbody tray, rather than from above the engine.
Key Access & Removal Details:
Access: Lift the vehicle on ramps/jack stands and remove the aluminum undertray (secured with 8mm and 16mm bolts).
Location Detail: Situated low on the passenger side where the engine meets the transmission, generally near the alternator level.
Fasteners: The starter is secured by three external Torx (E-Torx) bolts.
Hidden Bolt: A key tip from DIYers is that the third bolt is hidden inside a rubber damper at the front of the starter.
Safety Requirement: Crucial to disconnect the main battery in the trunk (and the auxiliary battery, if equipped) before starting, as the main power wire is always live
* this is from a US site and therefore it would, fairly obviously, be on the driver's side for RHD Mogs
