Is it permissible for a taxi driver to eat food items he found in his car and could not identify their owner?

If the food items are insignificant and their owner does not care about them, then there is no harm in consuming them. However, if they have value and their owner cares about them, then either they are not perishable quickly, in which case they must be announced for a year, like a lost item. Or, if there is a fear of them spoiling or expiring, then he may sell them and keep the price, announcing it for a year, or he may eat them and guarantee the price to their owner.