Does your phone charge with in home (plug into wall or computer) chargers? If the problem persists with those as well, it may not be the chargers. It could be your battery needing replacing, or it could actually be the port on the phone (which is attached to the motherboard) that needs replacing.
I would check the battery first (cheaper and easier to do). If that isn't it, then you have the option of trying to replace the motherboard yourself, taking it to a local tech/shop, or if the phone is still under warranty, contact Samsung to see if they can repair or replace it.
Yes, it charges fine in the house, I forgot to add, that I use the same cord,just the usb car charger is different so logic says it is the usb car charger part, but then I get stuck in the thinking that it works fine for hubbys grand prime why wont it charge my s3?
That is quite odd. Especially if it works in the home (the same cord(s)). Try a simple reboot of the phone and see if that resolves it. Sometimes, if people never turn off their phone, this can happen.
If that doesn't do it, I would try using a different connector for the vehicle and see if it works. If it still doesn't work for you, but does for him, it may be phone related (even though it doesn't seem so). I would check to make sure your port on the phone isn't damaged, loose, or has dust, etc., in it. Then if the problem persists, and you are under warranty still, then I would contact the manufacturer.
There are different types, however, most work well with each other. That said, some devices are extremely picky! My youngest had a phone that would only work with one charger cord. Never any others (different brands, etc.) and nothing I did changed that. It wasn't a standard issue with all versions of the phone either. She knew others with the same phone, but without the problem. Personally I think devices have personalities, just like people! LOL You might try replacing the part with the same part/from the same company that worked for you before, and see if it resolves the issue. That was the only thing that worked with hers.