u/ItalianResearcher Not car purchase- specific, but the following linked sites may be helpful. If you only plan to be in the States for a few years, you may consider leasing versus buying a car.

https://isss.uconn.edu/drivers-license/

https://oiss.yale.edu/campus-community-life/for-students/practical-matters/transportation-driving/obtaining-a-connecticut-drivers-license