Ameter ?s

Does anybody know of someone who makes a CT type ameter for a car?
They work like the CT type of electric meters where the main hot (or one of them in the case of 2 and 3 phase power) lead is passed through a coil type of sensor which picks up the ammount of current flowing through the main transfer wire. This would not put it in the charging path.
One of the main advantages of an ameter is if you have alot of draw, you can monitor weather or not there is a surplus going to the battery.
However with a volt meter there is no way to tell if you are over drawing the system.
Andrew