it's possible that the car got a replacement part eventually :) copper becomes ductile between 300-600 C ( https://www.engineeringtoolbox.com/docs/documents/13

it's possible that the car got a replacement part eventually :) copper becomes ductile between 300-600 C ( https://www.engineeringtoolbox.com/docs/documents/1353/temperature-strength-metals-SI.png https://www.engineeringtoolbox.com/docs/documents/1353/tempe... ) piston ring seals are usually made of cast iron or steel. copper would probably work too for a while, it's good at conducting heat, there's ample cooling in engines, so it wouldn't melt, just wear out very quickly ... and then the engine performance degrades as the sealing gets worse and worse (and it starts to eat oil, soot gets everywhere, exhaust becomes visible), mpg goes down, but ... the car would probably run. (loss of 1 out of 4 pistons is not a catastrophic failure)