I dont need to read the link. I am not saying your wrong but I am not saying your correct either as always, different rules apply in different regions of Turkey. Just saying your info is not accurate because here in Istanbul, they will not sell you a car without residence. how do I know this? because my company has helped many many people over the years with car purchases as its one of the services or company offers and it just simply cannot be done here in Istanbul, Ankara, Bursa or Izmir.
Its not the first time there are different rules for different things across the provinces as how to apply for a residence permit and what is needed is different from province to province which is annoying.