whiteducktail

If it came from your new car, the source of the fluid should be obvious by just looking up at the bottom of the car with a mirror. Unless, of course, it has been driven in the rain, snow, etc. since then.

BigT

ohniner, I feel your pain ! I have a 2018 GTS with 500 miles on it amd little driving in last 45 days due to weather. I found similar (same) situation on my car in garage. The leak which slowly leaves a small puddle on floor is emanating from the front edge of the black plastic rocker panel-where it meets the bottom trailing edge of the inner fender liner. There is a common screw attaching both of these parts to the body at that point. I like you was puzzeled about brake lines coolant lines, etc. Upon removing both inner fender liner, and rocker panel, and under body trays, I can confirm there are no lines in that area. All run through the center tunnel as has been standard practice for years.There are two possibilities-in that area above the leak is the very large reservoir for winshiield washer fluid.That fluid does not match my drops on floorwhich is more slippery. I speculate that there exists an overflow hose from the brake master cylinder resevoir over into the area around the washer fluid reservoir which I cannot trace.
fluid level was at the fulllevel but may have been higher when I took delivery. I have drained some fluid out, cleaned the car and await dry roads to give it a test.
will report back with results. I'm open to other theories as well.

ohniner

Finally took it down to dealer but leak subsided but still left some greasy streaks on left front rocker panel. Turns out to be ....wait for it....Windshield washer fluid! Svc Mgr says he's run into it before and that porsche utilizes a washer fluid that looks yellow and mimics the feel of a lightweight oil. My leak essentially stopped as reservoir ran dry. No issues driving car but appt. made to bring car in. Left front wheel must be removed so fender liner can be removed exposing washer fluid reservoir.

LexVan

Search "dirty nuns". We talked about this several months back.

Here:

https://rennlist.com/forums/991/974448-dirty-runs.html