But it's true that to book cars with no driver at Iwan Transport, all you'll need to provide is just a picture of your Identity Card. Exception is for during Eid Al-Fitr days, where down payment is not required at all.
YogYes.com is a travel portal to Yogyakarta with more than 100 places to stay, rent a car, and buy a tour. We have all their phone numbers. You can rent a house or car via WhatsApp, and easily negotiate with the owners.