Car Talk is a staple of public radio, even after the brothers Magliozzi have retired. It may outlast them, just as My Word! has outlasted Frank Muir by nearly two decades (Denis Norden, however, is still alive, in his 90s).
Four hour operas are somewhat excessive. They ought to break them up into two hour segments and present them on successive evenings--unless they are Wagner operas, in which case they ought to just stop presenting them at all, especially when they do something silly with them, as at the Met this year.