I've been using the "FMA Cellpro Multi4" for years. Most of the guys in my club that fly small electrics have one. It will charge up to 4S batteries with a max charging rate of 4.0 amps. You'll need the GP/KO adapter.
I might add that it is not a good idea to charge a Lipo inside a car. I set the battery on the ground a foot or two away from the car as a safety precaution.