I use a 3A charger in my car, but it's all wired in. Got myself one of these: http://www.ebay.co.uk/itm/DC-DC-Conv...item3ccbaa5de8
, a 3 way switch, 2 'add-a-fuse' things and wired it all up behind the dashboard with just my Micro USB cable poking out in the drivers side of the dashboard, which plugged into my old car cradle when I had the HTC Sensation. The switch is mounted in one of the blanking plates down by my right knee (right hand drive) and lets me choose between off, on and on-with-ignition for the charger. At the moment I have to plug it into the bottom of the Note 2 myself but I'm planning next to de the wireless charging mod, and integrate the charger into the cradle I have, with NFC also in there to activate car mode when I put the phone in the cradle for (IMO) the perfect solution with no wires trailed all over the car, and my lighter socket free for other things
It was all pretty cheap as well, and an easy mod to do - even though the cradle is on the opposite side of the car to the fuse box and I had to pull out the whole radio and centre console to route the wires... all hidden away now though.
I'll be doing the same on my next car as well.