Another coolant question

[1stmanin]

Okay okay..I know there are a MILLION post on this subject,but I cant seem to find something just like my problem.
I have a e34 530i.I havent had any problems until lately.My bloody coolant is disappearing.Okay,here it is.I will be driving,and the temp will go to the middle and hold while Im driving at a decent pace.If I slow down or idle,it starts to creap up and up.And when I park,I have a puddle 20 mins later under the car.My coolant is leaving and I hate it.What the devil could this be?

[witeshark]

How many miles on the car? When you check your oil, is there coolant/water at the bottom of the oil stick? The puddle may mean a simple leak and if you can't see it, then it may be at the back around the heater core.