Even if you have a USB port in your car, there's a decent chance it's all but useless. Most cars can't deliver enough juice to charge your phone -- especially when the phone is in use -- which is why you can watch it actually lose battery life when it's supposedly charging. The solution? Give up on the USB port and plug in a YI Car Charger with Dual-Port USB Qualcomm Quick Charge 3.0, which you can get for $4.59 by applying coupon code YI459Car at checkout. It lists for $13 and you can often find it for about $10; this deal puts it squarely in Five Below territory.
Why does this work? Unlike your car's USB port, which probably delivers an amp or less to your phone, the YI Car Charger delivers 2.4 amps through the 12-volt accessory socket (you know, the car's cigarette lighter, aka power port). That makes all the difference in the world. YI uses the Qualcomm Quick Charge 3.0 standard, which is designed to rapidly charge phones to about 80% in about a half hour. Even if your phone doesn't support QC 3.0, it'll benefit from the ports' higher amperage.
Because it has two USB ports, you can charge two devices at once. It's compatible with Apple and Android phones, tablets, GPS devices, MP3 players and pretty much any other portable gadgets you might need to top off on the road.