We used to have an '02 Saturn L100. If your L100 is exactly like ours was, with manually adjusting front seats, IIRC, the only place I could find to loop the rear facing D-ring tether connector strap for our rear facing Britax Marathon or Boulevard convertibles was around a metal bar that runs horizontally under the front passenger seat. This meant we couldn't move the passenger seat forward or back on its tracks after RF tethering, but we made the parental decision to use it that way because it wasn't possible for us to loop the D-ring connector strap around a recommended fixed point toward the front of the car, like a front seat leg or front seat track. If you're not comfortable with that option or would need to move the passenger seat on its tracks, Britax also allows you to tether rear facing "Australian style/method," directly back over the top of the convertible seat to the tether anchor behind the vehicle seat that would normally be used for a forward facing installation. Australian tethering makes it more difficult to place the kiddo in and out of the rear facing convertible seat, though, with the tether strap positioned over the top of the convertible.
