I liked your question but analogy of car vs car loan does not fit here because Bitcoin is not a physical good.

So exact question will be what makes BTC valuable. Below are the some factor.

Ease of transfer: No need to go to any third party, you are in full control of your money.
Transaction fees : They are constant for each transaction and do not depend upon how much you are sending but instead they depend upon your input/output, so it will be cheaper fpr big transaction.
Anonymous : You do not need to upload all your personal details  in internet to do an online transaction. For any other mode of online transaction you need to verify your phone number, address and so on.