What is the religious ruling on establishing a transportation company that relies on purchasing vehicles in installments and other facilities through dealing with banks, knowing that the bank acts as a guarantor?

The ruling on dealing with banks regarding car purchases depends on the type of bank and the method of transaction. If the bank is Islamic and buys and possesses the cars before selling them to the company in installments with a profit, then there is no harm in that. However, if the bank lends the company the price of the cars with interest, this is usury (riba) and is not permissible. Dealing with Islamic banks for facilities like guarantees is permissible if the Sharia (definition) guidelines are observed.