for a negative sentences is : i don´t have a new car , the don´t is when we can used the we they and it, the does n´t to she he and it. for example: she does n´t have a new car.
BRITISH
when used the British form we used the word "got" in all the subjects, but in third person is has in she he and it, we used have when we talk about i ,you, we and they. there the structure for affirmative sentences: i +have+got+ a new car, for a negative sentences is: i haven't got a new car ( only in short answers) but in long answers it is not used the " got because is redundant.
which one do you like more? what is you favorite?