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.
It is permissible for you to eat of what your father brings in that car, and to get in the car and benefit from it even if your father had bought it with a usurious loan, as we have already issued Fataawa 93774 and 102369 clarifying that the sin of a Riba-based loan is related to the person who borrowed the money and not on the money itself, and we clarified in Fataawa 87211 and 81560 that it is permissible to deal with a person whose earnings are a mixture of lawful and unlawful money and to eat his food. Therefore, you should not refrain from eating from the food of your parents or refrain from accompanying them when doing family visits with that car.
We draw your attention to the fact that if the car was owned by the bank and then the bank sold it to your father with a higher price because of installments, then this is permissible as long as the contract does not include any usurious condition, like paying a fine in case there is a delay in paying the installments and so forth. For more benefit on the conditions of selling by installments, please refer to Fatwa 82986.
Allaah Knows best.