What is the ruling on purchases made with money from interest-based bank profits, and buying a car through the bank with the deposited money as collateral, along with its interest? And how can my father dispose of this money?

It is not permissible to possess usurious gains. Rather, they should be spent on the welfare of Muslims or given as charity to the poor and needy. If a person buys something with usurious money, the amount of the usurious money must be disposed of, and he is permitted to keep what he has bought. It is obligatory to dispose of the amount of usurious gains that were used in purchasing the car. If the car was purchased through a Murabaha sale for a purchasing agent that did not meet the Shariah requirements, then there is no harm in benefiting from the car, but the amount of usurious gains paid in its price must be disposed of, along with repentance.