That is an extremely stupid idea. Get a credit card and use it for your expenses. Then pay it off in full every month, on time. That will build your credit without wasting $7-8k on interest payments.

Don't over emphasize your credit score, as it will naturally go up over time with consistent on time payments. Your score only matters when trying to make a big purchase like a house or car. And so you are doing this backwards.gwt your score up before you use it for a loan on a car, don't use the car to up your score.