Hi guys- trying to help a member of another board I frequent- no one, including BMW dealership knows the location or part number of the starter relay. AKA "we know nothing, bring it in so we can replace everything under the hood" I told him I suspect it's under the passenger cabin filter- but by not knowing which it is- it's all guess work. Any insight I can share with him? I will point him to this thread so he can add info too- he's got a 528i if theres any differences. his car has been down for a few days now, did everthing from new battery to new key- no power to starter. thanks guys- Mark