Yes. Or no. There are no stupid questions, of course, but this one is close. How the heck would we know?

Seriously though, welcome to Flyertalk. Do you work for Amazon? If not, that great deal you found may cost you a lot more than expected when they ask to see your Amazon employee id.

As for whether a particular discount code is "best and cheapest", the answer is, it depends, but sine you gave zero information about your rental, it's an impossible question to answer.