I just tried it and it worked for me. make sure that when you cut and paste the cdp# there is no spaces after it. I didnt go all the through the setup process because i dont rent cars very often, but i am pretty sure the codes were correct.
it works now. i signed up don't know if i'll ever use it but i have the option
Can you rent under 21 with it?
no
All kidding aside, are these things still valid now four and a half years later?