Leaking brake fluid. - L'escargot
A few years ago I bought a low mileage still-under-warranty 306. It wasn't long before I realised that it was losing brake fluid at an alarming rate. Unfortunately there were no visible leaks. It took me ages to persuade my local Peugeot dealer that the fluid must have been going into the brake servo. They finally agreed to investigate, and lo and behold......!

L'escargot by name, but not by nature.