All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
If the bank which gives the loan is a bank that deals with Ribaa (interest or usury) then it is not permissible to buy the car through this bank. That is because a bank that deals with Ribaa gives a loan with an additional amount which it calls a profit, and this profit is nothing but Ribaa itself, and this is forbidden in the Book of Allaah and the Sunnah of the Prophet . Please refer to Fatwa 88400 on the ruling of buying a car with a loan from a bank which deals with Ribaa, and Fatwa 81375 on the seriousness of Ribaa.
However, if it is an Islamic bank which provides a loan without interest or that it buys the car and it owns it and then sells it back to you at a higher price after having fully taken possession of it, then this is permissible and this is not considered as Ribaa.
Since the bank gave the choice to your husband to choose from any bank he wishes, he is obliged to opt for an Islamic bank if the latter will provide him with a loan without interest or that it will buy the car and then sells it back to him. However, it is forbidden for your husband to go to banks which deal with Ribaa.
Allaah knows best.