Car finance is just an example of where a bank can create credit w/o deposits. I just picked that because people are familiar with it. You go to BMW to lease a car. BMWFS creates a loan to itself out of thin air. BMW buys the car then rents the car to you. Then They pack these leases together as an asset backed security and these papers are used as money. No deposits required
Why should BMW buy you a car if they can produce it for you? In this example BMW serves as a central bank. I still don't understand the essence of your example.