Two things: ASA is always going to be my name for it - ISO seems ever so much part of what´s politically correct, in some strange way, designed to offend on-one, change for change´s sake (to me).
The other thing is that, whilst it may feel strange for Angelinos to refer to their roads with the use of a definite article, in other, less - here we go again - newspeak countries, it is pretty well de rigueur to use language in that manner. It might not sound quite right in song, but out of that context of suspended thought it is different. One wouldn´t say I´m going north today on M1, it would always be the M1. That´s not to say that it would, of itself, be a brilliant idea. You would run into over-congestion and many dreaded white-van men. In fact, you could argue that the entire concept of going northwards is not a really thrilling idea, perhaps why I decided to live much further south.
But really, being under forty is no crime - to tell you the truth, it would be much nicer going back there than going north.
Rob C