Originally Posted by Bamaben
must be normal for bmw's. i've had the system pressure checked at the dealer which they said was ok, so did my indy shop and I still have to add about a cup of coolant every 3 or 4 months or so. my indy shop said that bmws tend to evaporate the water out of the system, not so much the coolant, so when you top it off to use just water.. I still top mine with a 50/50.
For a contrary experience, I've only had to add coolant once to a BMW in over 10 years which includes 5 cars with a total of more than 200,000 miles.
I once got a coolant warning after parking my Z4 on an incline, but it was fine on level ground.