The Magic Flight Car Accessory gives you enhanced flexibility by allowing you to power your Magic Flight Power Adapter 2.0 or Magic Flight Battery Charger through your car's 12V port while you're on the road.
Note: The Magic Flight Car Accessory will not power the Magic Flight Launch Box directly. It can only be used to power the Magic Flight Power Adapter 2.0 and Magic Flight Battery Charger.
The car charger is great if you only use batteries. The power adapter comes with a car charger though, so I would just skip straight to that next time.