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I have a sloped driveway. Does carwash mode always disengages the parking brake? The main reason I haven't tried it. I just disable the folding mirrors and I can wash the car just fine.
You can also keep your phone out of range, or disable Bluetooth on it, when washing the car. (Obviously, if/when you do anything that requires opening the doors, you'll need to go get the phone or use your key card.)