Zipcar/City car club tech for unlocking cars...?

[MrH]

Does anyone know what the technology is behind zipcar and citycarclub (and others im sure) members being able to unlock and start cars with an app or membership card?

Would just like to know what it is

Cheers

Mark

[Du1point8]

You don't, the membership card/app only unlocks the doors, the keys are inside.

presume its a simple card reader like the oyster hooked into the door mechanisms that only open when its your turn.