Breakdown Of Many To Many

I was wondering if somone could clear something up for me.

I understand that if there is a database with for example:

table_Cars(reg_num)
table_Customers(cust_num, cust_name)

there is a many to many relationship and so the inclution of

table_Order(hire_date, reg_num, cust_num)

would eliminate this.

I understand this but where I get confused is what would be done if a customer could hire out more than one car on the same order.

a Car can have MANY orders and and order can have MANY cars.

back to square one.

any guidence on this subject would be appriciated!

thanks