Your car is a tough environment for a wireless charger. A car can be very hot and very cold. And a badly designed wireless power transmitter could interfere with sensitive electronics in your car. Potentially disabling the car, or your charger.
The Automotive Application Group (AAG) of the Wireless Power Consortium developed guidelines to assist developers of wireless chargers for the automotive aftermarket. These guidelines help to develop attractive Qi automotive chargers that deliver the promise of Qi.