It’s a 2012 650iIf your talking about the 650 with a coolant smell, 99% chance it’s the hoses feeding the turbos. It’s actually an easy repair if you can get some hose material. The “proper” repair is to replace the entire lines, metal and all, but it will do it again in time. The crimp type hose clamps start to loosen with the heat from the turbos and will seep, then eventually leak. People also tend to overtighten the hose clamps which makes them leak faster as well.
Pretty sure it’s a leak from an intercooler that will require the motor to be dropped. At least that’s what she was told.
I did find guides on the leak you’re talking about. I would DIY it, if I could.