Turkey is packed with local rental spots that offer way better rates than the big international desks at the airport, especially on smaller hatchbacks and sedans that sip fuel. Main things to watch are whether unlimited mileage is included and what the excess on the insurance looks like, some places list dirt cheap base prices but the deposit requirements are wild. To browse economy rental car in Turkey options from local fleets you can check out this aggregator
https://turkey-rentcar.ru/en/catalog/economy/ .