Is the price difference in murabaha for car financing considered usury? And is it necessary to inquire about the source of capital funding even if it is said to be a benevolent loan? And is it permissible to resort to Tawarruq due to the lack of an alternative?

Murabaha is permissible, and its profit is not usury. It is a legitimate alternative to prohibited transactions. Allah Almighty said: "But Allah has permitted trade and has forbidden interest." The client is not required to know the source of the bank's or seller's capital.