Car paranoia. An oil stain has appeared where I usually park my car, but I don't always park there. There is also a patch where I sometimes park when I can;t park where I want to park.
A sheet of cardboard under the car to catch any drops, checking the dip-stick, checking the car's own warning systems. These all prove that there is no oil leak, but at more than 130,000 miles I'm always expecting something.
Something other than the ruined handbrake, sticky boot lid release, leaking AC radiator, and low-frequency vibration at motorway speeds.
Not being able to trust the thing makes me not want to do long journeys. That, and being cooked alive because of the faulty AC.