He mistreated his wife so as make her register the car in his name
The confusion is that :--
Is it unIslamic for the wife to not give that money in husband's hand at the first place? Was it obligatory for her to assign that car to husband's name instead of her own?
Is it Islamic for her husband to misbehave and not fulfil the basic needs of her because of that action.
Is it not husband's duty to be responsible for all basic needs of kids and wife? Is it flexible for him? Is it only sadaqa from his side, if he spends?
She does not have to give the money to her husband. Her money is hers, unless she willingly gives up something to her husband or her brother or to someone else. She does not have to register her car in her husband’s name unless she has given it to him willingly. On this basis it is not permissible for her husband to mistreat her in order to make her give up some of her wealth. He is obliged to spend on her from his wealth, not from her wealth, and to find her safe and suitable housing, just like any other husband. The same applies to his children. If he spends on them seeking thereby reward from Allaah, he will get that, if Allaah wills, even though that is regarded as his duty.