The car in question is my friend's 2006 Buick Lucerne CX. Coolant leaks from the engine assembly somewhere and drips off of the bottom of the car on the left side, around where the engine meets the transmission, toward the back of the car. It is almost certainly not coming from the water pump or coolant elbows, I can see those clearly and it is dripping from the other side of the car entirely. I replaced the elbows with aluminum ones a year or two ago. I can see the heater hoses and their connection to the alternator bracket and the firewall are not leaking. I'm not sure exactly where it is coming out, have not been able to get underneath the car yet. There really isn't any coolant visible on what can be seen from the top. Could this be from the manifold gaskets or something else like a core plug? (Are there core plugs in the end of the engine attached to the transmission?) There is no sign of coolant in the oil or going into the cylinders-- I thought most intake gasket leaks were internal-- and also this is a series 3 which was supposed to have relatively trouble-free gaskets. Relatively in GM terms though.