I had a mid 80's Volvo 760 that was suffering from crumbling insulation so I'd expect other euro cars to have suffered a similar fate.

When I was investigating purchasing a 95 SL500 ,a call to the parts dept asking about wiring harness insulation failures / availability netted the guy saying. " Oh , horrible! Jags too. . ."

To those that can see insulation crumbling, replace / rebuild the entire harness soon. It is the wires that you can't see that will cause problems from stalling to damaged electronic components to fire.

Another issue with these cars is that the entire car is wired with the stuff, it's just the engine harness that sees failures first due to the high heat. The front body harness will the be next to fail.