Many rental car agencies are upgrading to the latest GPS technology. Budget Travel rated several and this is what they found.
Enterprise rents the Garmin nuvi 265W for $10 a day.
Hertz uses their own brand for $13 a day. This one is fixed below the dashboard so be careful when parking as it cannot be removed and placed out of sight.
Avis/Budget has the Garmin nuvi 780 for $14 a day. Budget Travel really likes this one as it is a newer model and will even give you real time traffic updates.
Dollar/Thrifty rents the Garmin nA1/4vi 660 for $12 a day.
Alamo/National has the Garmin StreetPilot c330 for $12 a day.
Each have pros and cons so do some checking if having a GPS is the reason you are renting from a particular company. Happy navigating.