There are many USB chargers across vehicles and as such it is difficult to know if your USB offers enough power for charging the iPhone 6. If the vehicle has an integrated USB charger and it doesn't have the needed power, then you may need to purchase another charger for the car. There are 12V DC chargers that do offer the needed amps to charge the iPhone or you can purchase an Inverter that will charge the phone with USB and/or AC ports. Many Inverters take up little space, have fans that are so quiet you wouldn't know they have a fan, and cost around $30 USD.