I am not sure why you are having an issue with this. Do you understand that modern cars are not made by people - they are made by machines. Machines can be fairly easily designed to build engines and body parts, as well as assemble them.
I am well aware of automated manufacturing. I design it for a living.
Do you realize how big a Ford factory is? If you are going to have a self replicating Ford that manufacturers itself, you are going to need to duplicate all the functions in that factory. And you are going to need to duplicate all the functions in the factories of the suppliers, such as makers of tires and computer chips. Then you are going to need to include all the functions in the factories and contractors that build all these factories, and everything that builds those factories, etc.
And no, cars are not made exclusively by machines. There are thousands of people involved. So if the cars are really going to make themselves, you need machines that do all the maintenance and machine attendant functions currently done by people.
And then you put that all on wheels, and you end up with a "car" about the size of Detroit.
It probably could not even be done by a single machine, but hundreds of cooperative machines that together do all the functions and together build all the machines, perhaps that could be done. But that huge mobile factory wouldn't really be what we call a "car".
That would depend on how it was programmed. To see evolution you would need to have some programmed design that is passed on to new builds, which can contain errors, and then some external selection process to decide which models were fittest.
This wouldn't have to be a formal blueprint of coure. Imagine a machine that lived in a very large junkyard. It could move around and pick up scrap and could use that scrap to build new machines. It's programming tells it to make a new machine as similar to itself as possible, but since the scrap bits are random sizes there is some variation in the builds. Now imagine environmental hazzards in the junkyard. Some of the new builds will be better at surving these than others, so will survive more frequently to build new machines. After meny generations the machines will have "evolved" to cope with the hazzards more successfully.
A group of machines such as mentioned above could also evolve by running genetic algorithms in the computers that run the system. The computers would run programs in the background to simulate how everything works with the real world conditions, and the computers could test new parameters to see how they would work. They could then modify each new generation of machine based on what they find. The result could be a continuously modifying factory system.
So giant factories on wheels could conceivably build themselves. But anyway, your point of all this is what, exactly?