You need a 12v to 5v adapter as said. It's on the site: http://www.toysinyourcar.com/acatalog/intravee.html
or here: https://www.amazon.co.uk/LAYEN-i-CHARGE-converter-compatible-Convertor-Black/dp/B00BFXPBD2
Mine is useless though and any movement the phone cuts off the car, so I removed it and don't charge. It is a lot more reliable without it. Also makes more of a mess of the cable in the cabin. Why there isn't a lightening style cable now, I don't know!
or here: https://www.amazon.co.uk/LAYEN-i-CHARGE-converter-compatible-Convertor-Black/dp/B00BFXPBD2
Mine is useless though and any movement the phone cuts off the car, so I removed it and don't charge. It is a lot more reliable without it. Also makes more of a mess of the cable in the cabin. Why there isn't a lightening style cable now, I don't know!