Is it permissible to buy a car in installments with an increase in price that is directly proportional to the installment period?

It is permissible to sell by installments with an increase in price, but it should not be stipulated that the increase is interest separate from the price. If that occurs, the sale is either reprehensible (makrooh) or forbidden (haram). The correct method is for the seller to determine the value of the commodity and their profit, then inform the buyer of the total deferred sale price without detailing the increase.