Is it permissible to deal with Zitouna Islamic Bank in Tunisia to purchase a car, where the bank buys the car and pays its price, and the customer pays an initial amount to the bank and the remainder through monthly installments?

If the bank adheres to Sharia controls in its transactions, then there is no objection to dealing with it through murabaha or other means, provided that the bank owns the commodity and it enters into its guarantee before selling it to the purchaser, and that the price is specified and known in the contract, not increasing with delayed payment. There is no objection to paying an initial percentage of the price upon contracting.