What is the ruling on selling a car for an agreed-upon price, where part of it is paid in gold, and the remaining amount is agreed to be paid in specific grams of gold, knowing that the price of the car is increasing and the value of the currency is decreasing, and what should be done if this sale is impermissible?

If the sale contract stipulates that the remaining amount is 32 grams of gold, then there is no objection. However, if the remainder is an amount equivalent to 32 grams of gold in Lira, then it is not valid because the price in that case is unknown. Scholars have stipulated that the price must be known for the sale to be valid, and they agree that selling an item for an unknown price is فساد (invalid/corrupt). The contract is not valid if the remainder is 60,0 Lira, on condition that it be exchanged at the time of payment for this weight of gold, because it is like a deferred currency exchange and not at its daily rate. It is stated in the resolution of the Islamic Fiqh Academy (30217) that it is permissible for the creditor and the debtor to agree on the day of payment to settle the debt with a different currency at its exchange rate on the day of payment. However, it is not permissible to agree to register the debt as equivalent to its value in gold or another currency, with the debtor committing to pay the debt in gold or the other currency. If the sale is فساد (invalid), it is annulled, the price is returned to the buyer, the item to the seller, and a fair rent for the period it remained in the buyer's possession.