Guido io was given as the translation of I drive.
Why not just Guido or Io guido or are they all correct?
They all are correct, but "guido io" means that the person is saying "I will drive now"="I drive now". It's sort of exclamation. :)
"Guido Io" in Italian is an imperative, an action that you want to do or you will do, while "io guido" is a present tense, an action that you do in the moment you speak. Suggest by an italian mother tongue, sorry for my english.
It's a matter of emphasys, when the subject is put after the verb you're making a stronger statement about it, without context they are all correct.
Guido io (non tu o altri) = I drive (not you or somebody else).
All of them are correct, but I think that it is related to the context; "Guido io" can be seen as an imperative verb, for example two friend go back to the car and one says " Guido io" meaning "I drive and I don't want to negotiate with you". "Io guido" it's the present tense "I drive" usually followed by somenthing else in the sentence for example "Io guido l'auto" can be translated "I drive the car". About "Guido" alone I will use it only in a context of a question, "Cosa stai facendo?" re "Guido" translated as " What are you doing?" re " I drive" but with the meaning "I drive...don't bore me with your question "