I am a 21 year old UK citizen and want to travel from New York to L.A with my girlfriend (also 21) in the summer.
We both have full UK British driving licences and were thinking of buying a car on the East Coast and selling it later on at the Pacific Coast. We will get International Driving Licences.
How much could we expect to pay for a car in the New York area?
How much could we expect to pay for insurance?
Thanks for any help. 
To have insurance, you will need to have a permanent address in the United States. Since you don’t, you won’t be able to get insurance on that vehicle. You’re better off renting one for unlimited mileage for X weeks rather than buying a car.
First. You don’t need an International drivers Permit. They are useless and a waste of money. Their only purpose is to translate your current UK license……into…… ENGLISH ! (and nine other languages) Your valid UK license is all that is needed in the USA or any country in the world.
A car in New York will cost any amount you choose from $500. to $50,000.
The price of Insurance is based on the car, the drivers and a dozen other things. I suggest you call or email a few NY based insurance companies to get an idea of what they may charge you for their insurance.