I rented this vehicle in CA on a business trip. My fully charged GPS device (charged from home) was plugged into the Sonata's accessory output under the dash. The charging light was ON but the GPS device lost its charge after about an hour of operation. It would not work again for 3 days even though it was plugged into the Sonata's accessory output. When I returned the vehicle, returned back home and then used my own vehicle (Ford Fusion), the GPS worked fine and charged fully and correctly. My estimation is that the accessory output in the 2016 Sonata does not provide enough voltage for most GPS devices to charge fully. This means that it may work intermittently or not at all. This should be checked out by the company.