Since putting a security code on a windscreen (for everybody visible) sounds rather silly, the answer is no. The security card (creditcardsize, blue, key on it) could be in the security-envelope you describe. It has a 5 digit securitycode on it.

gr J

Thanks for the above post. I couldn't find anything like you describe with a 5 digit code. Looks like I will have to contact Fiat.