Vabbè
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It's the contraction of va bene. Depending on the voice tone, it can express several (mostly negative) feelings. In the example of Max.89 it could show a bit of resignation because he wasn't able to borrow the car. He may say it never minds (fa niente), but this vabbé is a signal that, in fact, he needed the other's car and now he has to look for another solution. It depends a lot on the tone, here.
Vabbé can often be a reply to withstand some advice (like saying: yes, you're right; but...):
Policeman Guardi che non può lasciare la macchina qui!
Me Sì, vabbé, ma è solo per cinque minuti...
Policeman No, la deve spostare subito perché intralcia!
Me Vabbé ma dove la metto?? Non c'è parcheggio!
What I wanted to show is that vabbé does come from va bene, but can't be used in place of it: if something is really good for me, I'll say Va bene and never Vabbé. The latter would mean I'm not so happy nor satisfied in fact.