Is the Murabaha loan for purchasing a car, in which a commodity is sold by the bank to the customer in installments with the option for the customer to sell the commodity or for the bank to do so, permissible or is it Riba?

If the bank owns the commodity it sells in installments, or purchases it at your request, such that it genuinely enters its ownership and responsibility before being sold to you, then there is no harm in that transaction. It is, however, better that you undertake the sale of the commodity yourself, inspect it, and take possession of it before selling it.