You will pay extra if you request GPS.
Most rental cars do not include GPS, you will most likely be charged for one at the counter unless you specifically requested one and paid extra through expedia.
How do you know the car has a GPS? Some times the car Expedia shows is not what you get at the counter, it will be of the same class. If you think all cars in this class comes with a GPS, then take the rental without an extra paid GPS, then go check the car and if that specific car they gave you doesn't have a GPS, go back to the office and there is a counter on the right that does Rental car changes, go there and ask them to add the GPS if you want a GPS.
If the car has GPS built in then you shouldn't be charged for it but it doesn't hurt to double check at the counter before signing
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