2004 Cadillac XLR Owner's Manual - Page 34

You can use these lower anchors to install the child seat instead of using the vehicle's safety belts if the child seat has the necessary attachments (A, B). However, your vehicle does not have a third anchor, called a top strap, or tether, anchor (C). If the instructions that come with the child seat say that it must be secured at all three anchors, do not use that child seat in this vehicle. See Top Strap on page 1-27. 1-28