I am confused with this one scenario part, and i dont know if i am doing this correct. Here is the one scenario:
- a customer may order one or more cars, but each order is for only one customer.

Here is my interpretation as a E-R Diagram:

Is the relationship correct?
Thnx.

Ask yourself some more questions:

Can a customer place order for one or more cars in a single order?
or
Each Car has to be ordered on a separate order?