Aukey Four-Port USB Car Charger
If you are on the road a lot and need to be able to charge several devices at once, look no further than the Aukey CC-01 four-port USB car charger. As noted by The Wirecutter, it can simultaneously and relatively quickly charge two iPads and two iPhones, no problem. You’d think it would overheat under such conditions, and it does get a little warm, but not enough for concern.
Note: the four USB ports are arranged in a long row, but since you can plug it in vertically or horizontally, space shouldn’t be an issue for most vehicles. Your mileage (no pun intended) may vary.