As for the child support calculators they are generally correct. Mine is exactly what the calculator brought it out to be. As for when the child support is adjusted. By what I have been told is that at any time you can get a re-evaluation done to determine if more or less child support is owed. CSE (child support enforcment) recommended to me getting a re-evaluation done every year. For the vehicle thing, i am not sure about that. I would assume if its in your divorce decree that he pays for the vehicle since he got the car that he would still have to pay for it.