What is the ruling on the car that the questioner's brother purchased in installments, and the transaction included life insurance in the name of his deceased friend, especially since the company informed the brother that it had become his property?

Your brother must go back to the insurance company to change the transaction to his name, or at least inform them of the truth of the matter. Otherwise, his silence would be a deception and an unlawful consumption of their wealth. Allah Almighty says: "And do not consume your properties among yourselves through falsehood."