This is pretty simple: a car lighter cover (or replacement car lighter plug) that looks like a whimsical button you’d see in a James Bond car. The button would be labelled “Passenger Seat Eject” or “Missiles” or “Machine Guns” or what have you. Personally I would go with the Seat Eject one to intimidate passengers. It being plugged-in the cigarette lighter this could also illuminate (repeatedly blinking on and off) for a more authentic look.
Much like my Spy Hunter car stereo design, I always thought it would be fun to add a bunch of fake buttons to the console of your car for that “double-0 agent” feel. Maybe something can be done along the lines of a USB charger that plugs into the lighter (I might have to tackle that design one day).