What is the ruling on the transaction of buying a car in installments from a bank that deals with interest, knowing that the bank is an intermediary between the buyer and the car dealership, and what is the ruling on the money resulting from selling this car and using it to buy land and build on it?

If the bank pays the price of the car to the buyer with interest, this is forbidden usury (riba). However, if the bank first buys the car for itself, then sells it to the buyer after it has entered its possession and responsibility, there is no harm in that. The criterion for the permissibility of the transaction is the bank's ownership of the commodity and its entry into its responsibility before selling it to the buyer. As for an interest-based loan, its prohibition is related to the liability of the one who takes it, and it does not prevent your friend from benefiting from the price of the car in buying land or other things.