I'm sort of famous among my friends for losing things, and I've left probably four or five things in Hertz cars to date. My recovery rate is better than zero--I had a wireless computer mouse found and held for me at KOA (a friend heading there a few weeks later picked it up for me), and more recently I had a jacket found and shipped to me from DFW. A Bose Bluetooth headset I lost at DCA probably four years ago was never found, but those are so passé nowadays, so no big loss, I guess.

So it's definitely worth filing a report. No guarantees, but better than not doing anything. It seems to take them several days to find and process lost goods, but if you haven't had it found within a week, I'd say, then you might want to give up and go get it replaced (assuming you actively use it and don't want to wait).

Note that Hertz's shipping+handling fees are a little ridiculous ($33 to ship my 1.5-lb jacket that could have come by FedEx Ground for $16 or been easily stuffed in a medium USPS Flat Rate box for $14). It's possible they might be less ridiculous for something that can fit in a #10 envelope and go out with a 49-cent stamp, though.