2017 Carrera S with 42k miles. Came across this staining on the very front underbody panel just behind the front wheels in the center. Seems to still have moisture. No trips in the rain recently. Anything to be concerned about?

 

I've taken all of the undercar panels off on my 2017 C2S for inspection -- after I found mouse droppings under the frunk lid along the right side near the strut tower top.

Possible sources of liquid and evidence of dried liquids:

1) Engine coolant radiators are located inside the front fenders in the front walls of the inner liners in front of the front wheels and the plumbing for those radiators runs through the tunnel to the engine. That would be my first guess and concern -- possible leakage of coolant. [My coolant pump began leaking but never dripped on the floor; it just stained the bottom of the pump and the coolant cross pipe.]

2) The battery is located above. It shouldn't be leaking anything, unless the plastic case is cracked. My car came with an AGM type battery which shouldn't leak regardless of installed position.

3) The brake master cylinder and plumbing. Brake fluid is corrosive, and quickly damages paint.

4) I don't know where the A/C cabin evaporator drains are located; they may be located further rearward. Someone else can chime in on that.

5) I don't know where the front sunroof drain lines are located, but think they exit near the sides of the vehicle near the A-pillars.