Is it considered usury for a brother to repay the amount he borrowed to buy a car as is, knowing that the car depreciates and its value decreases over time, while the lender refused to take interest like a bank and proposed a 45% share of the profit without participating in the loss?

If you lend your brother money to buy a car, you are entitled only to the amount you lent him. The car, along with its profit or loss, belongs to your brother. It is not permissible for you to agree with him to take a percentage of his profit, as this is usury (riba), which is unanimously forbidden. However, if he will repay you the same amount in installments without any increase, this is permissible and not usury.