This story may sound unbelievable but I can assure you that it is true.
A friend of the family bought a brand new Renault 18. I don't know the exact year but it was in the early 80's.
Proud and happy he was driving with his new shiny 18. That was for the first 6 months. After this first period of joy you could here a noise. A noise that couldn't be located. Well after a while he found out on the high way where this sound was coming from. Just out of the blue a part fell out the floor of the car. A hole...almost a feet in diameter...like a extra porthole to have a closer look at the road under the car. He could laugh about it later and talked about the Flintstones car....at the time he was not happy at all with his children in the back seat.
The reaction from Renault at that time was that it was no problem to repair it. Welding the missing part should solve the problem. With a car younger than a year the warrantee should be enough to expect a new car looking at the size of the problem. According Renault in France a steel factory has to use a large amount of recycled steel ( back than ). On a Monday morning when all machines have to start up it just can happen that the temperature is not high enough to mix the recycled and the new material in a proper way so strength and cohesion is good enough to last for years. Eventually after a long period Renault offered him a new car. You can imagine that he refused that offer. Just for safety reasons he purchased a more reliable car.
Note ( I don't want to give the impression that Renault is making cars that are not reliable. This was years ago the idea of the person who was involved )