I'm not sure if transparent overlays work properly on newer Nuvi models. I tried making a few myself and they didn't seem to work on my Nuvi 3550 or Dezl 760. Did not do any serious troubleshooting. But I have asked on this forum and elsewhere, and did not get any responses as to whether the newer Garmin automotive units can use overlays.
Maybe someone else will post whether or not it works on a recent Nuvi? Otherwise, my guess it that it's not compatible.