Q:

I have bought a car this year too

I have bought a car this year, too. 

What does this sentence mean? "Me, too," or "I have done something else and have bought too," or "I have something else and a car too," or "this year too." And how do I emphasize one of these aspects in particular?
In my language, if I want emphasize something, I put "too" directly after it. For example, if my friend bought a car and I want to emphasize that I did too, I might say "I too have bought a car this year." If I put the word too after "bought," it means I did some action and bought too, If I put too after "a car," it means "I bought a house and a car, too," and so on.

A:

It can mean a lot of things. Specifically, the 'too' can relate to almost any constituent in the phrase.

I have bought a car this year too. (As well as my friends have.)
I have bought a car this year too. (Next to the car I inherited.)
I have bought a car this year too. (I have bought a lot of things.)
I have bought a car this year too. (I bought another one last year.)

One way indicate your meaning is by word stress; any of the above options can be made plainly audible when spoken. Writing does not offer this possibility (unless you want to italicize); often context favours one of the interpretations over the other ones. If not, one can disambiguate by rephrasing or expanding the sentence (for example, by adding extra information that makes the intended meaning clear, such as the parenthesized clauses I added). 
NB. "I, too, have bought a car this year." is idiomatic. "I have bought a car, too, this year." sounds still OK to me but already ambiguous.  

