I have a 2000 328i. I have had it since October 5th. Recently my headlights and right turn signal have been blinking. We thought it was the alternator but that wasnt it. My engine revs up when it is idle. Soon after my heat did not work. It only blew out cold air. Also my car started overheating and i would constantly put in more coolant. And finally it would cut off at stoplights occasionally.
What causes your headlights and turning signals to blink? on 2000 BMW 328i
I think the heat and the lights are 2 different concerns, make sure you have good ground connections for lights by load testing them. By you having to constantly add coolant it sounds like either an external leak somewhere or internal like a head gasket or god forbid a crack somewhere.