Buying a Car/ Opening a Bank Account

These guys specialise in this sort of thing.

VademecumItalia

Try them then report back.

There is a shortcut to Opening a Bank Account:

1.   Find the "ENTRATE" office in your area.   (Entrate is a government Agency that is responsible for keeping track of people in Italy.   In Italy, like in France, and probably other European countries, the government must be informed where you live, etc.)
2.  Request   a "CODICE FISCALE"  -- their equivalent to Social Security Number.   You need to show your foreign passport and tell them your address.     There is no need for Permesso di Soggiorno or other long-term residence status for that   (It used to be the same in the USA many years ago.  Now obtaining an SSN is a bit more restricted in America)   I was issued the Codice Fiscale on the spot, and it is free of charge,
3,   Take your new Codice Fiscale to any reputable bank together with your passport and some money and the bank will open an account for you.
4.  With the Codice Fiscale you can also rent an apartment, get utilities accounts, even supermarket frequent shopper discount card.

I did not try to buy a car, but almost certainly they will also prefer you to have a Codice Fiscale.

Good Luck

Thanks refusenik, but I was hoping to do this without incurring further avvocato expenses. I have already racked up a substantial bill getting to this point without enlisting another law firm.

So I presemted myself today at thee Agencie Entrate lbut they referred ma back to the Commune where I have already been twice. The entrate looks after Codice Fiscale (which I had already obtained  before I left Melbourne) bur not registration of residency.

I have a confirmation slip for my appointent at the Questura for my Permesso in December, I will take it back to the Commune tomorrow and see if I can get them to register me even tentatively until then.