I just moved back to the US, and this is my current dilemma. I spent 7 years living in a city with good public transportation and a very affordabl bicycle rental system, so I never cared to get an international driving permit or learn how to drive a motorbike. Now I am forced to look at a car to buy. Unless you're in the densely populated cities in the Northeast (ex. New York City, Philadelphia, Washington DC, etc.), a car is 110% necessary.