Do car rental agencies accept secured credit cards?

Yes, Car Rental Companies accept Secured Credit Cards. There are two types of cards. "Secured" and "Prepaid". Prepaid cards will be accepted at rental companies (or will be treated like a debit card). SECURE cards on the other hand are not like a credit card. The rental company has no way of knowing rather the card is secured or not.

All secured cards say "debit", and have a Visa, MasterCard logo, etc. However, as with any credit card (secured or su-secured), they will take a deposit out on the card that covers the rental fee for your expected term. This will not be "charged", but "held" to your card until you return it, at such a time you can choose to authorize the payment to go through or pay the balance with a debit card, allowing the hold on the credit card to release.