What matters is not the brand being 100% Turkish owned (which cannot happen anyway as those 5 companies are not 100% Turkish owned.), but as much of the production of the car as possible being done in the country.
Depends what the goal is here. If it's to make a Turkish based car manufacturer then you would expect factories to be opened up around the world to meet customer demand. If a Turkish produced car takes off but only manufactured in Turkey, it would be less competitive in the N. American, East Asian markets. So opening factories in that part of the world would make sense.
If it's to provide jobs in the industry and boost the number of cars built in Turkey then there are other ways of going about it. Turkey is the 7th largest auto producing country in Europe. Countries with a more expensive workforce, UK, Germany, Spain, France, are still producing more cars. Having domestic car makers helps with that but surely Turkey can improve on it's position considering its cheaper workforce and location which can service Europe, Asia, the Middle East and Africa.
The government would then better serve by providing incentives to build efficient factories, provide workforce training, education to provide high end skills and smarter factories.
Probably it's a bit of both. A domestic car to compete with other countries that have their own auto companies, and the increased production will help with job creation and boost exports.
The UK, which is above Turkey in the number of cars produced doesn't really have a UK owned company anymore. Jaguar which is still headquartered in the UK is owned by Tata. Most cars built in Britain are foreign owned companies like Nissan, Toyota and Honda. Nor are British built cars for the domestic market. 8 out of 10 cars built in the UK are exported.
This isn't to boast. Britain isn't as strategically located as Turkey. British workers require higher pay and generous rights. Britain got this higher production level because it persuaded companies to invest in British factories. For example, the land for the Nissan plant in Sunderland was sold cheaper than the land value. After Brexit May offered Nissan a deal to stay which we still don't know the details off.
Diplomacy, facilities and a skilled workforce is the key.
https://www.smmt.co.uk/2017/01/17-y...nufacturing-global-demand-hits-record-levels/