My wife tells me that her X5 is telling her that the coolant is low when she starts it. I drove it Mon., 02/27 and again on Tue., 02/28. The trips were short, no big deal to have to walk home, but that didn't happen. Both times, I put the car in the driveway so I could see where it was leaking from, but it took 1.5 hours to leak anything at all.

It's hard to tell so far, but I'm going with the water pump because that's a common problem with the M5x engines.

This engine has an auxiliary pump that I have not had in any of the earlier engines. How prone is the aux water pump to leaking, and why would any leak take 1.5 hours from when I park to when the leak appears on the ground under the car? The HVAC system does not have any indications that it will cycle coolant -- the job of the aux pump -- so I have no idea how to make it work, and I don't really care. But the aux pump is there and I'm having a leak so I have to wonder what conditions would make it leak after 1.5 hours of turning the car off.