[bb_zetec]

I think also parts availability and electronics has something to do with it.

Yes as others have said rust was the killer on the older cars, mechanically there were simple without too many electro-doo-dads that can go bad and kill it.

A mate had an old 80's Jackaroo that went well over 350,000Klms but couldnt get any more parts for it so it got junked.

Once it becomes unreliable to a point that also signals its death, look how many EF/EL/BA's got send to the wrecker due to failing electronics.

Mechanically they could probably keep going for 100,000s of more K's, but the end user gets so frustrated they get rid of it.

Modern cars will die due to electrical faults. Mind you the electrics of today are much better quality than the 80s stuff, but there is so much more of it that it simply will become cost ineffective to fix.