Quality cannot be 'built' into a car. It has to be designed in from the drawing board. With proper design and manufacturing techiques cars cannot be built poorly.
If you design the parts of a car with 3/4" of slop for adjustment, then guess what? You get slop.
Infinity/Nissan discovered it was too difficult to get a consistent build due to the car flexing as it moved over the factory assembly floor. So, they built a factory where the car sits in one place and the assemblers (robots and/or humans) are moved to the car. Not only did it improve consistency, but they were able to tighten up the play in the car.
It was also easier to use robots for assembly as the robot could be more accurately placed than trying to accurately place the car in proximity to the robot.
Materials are the next issue with American cars. While we have very good metals, the rest of the car really lacks. One thing I notice about current American cars is how the interior degrades really quickly. They fade, crack, break apart at seams and just fall apart in a few years time. This is just poor/cheap materials.
My 10 year old Infinity I30 interior looked brand new when I got rid of it. I did nothing special, it just looked really good. Conversely, my neighbors 4 year old Chrysler looked really bad. He now owns a Lexus.
There is not an American car in any driveway of the block I live on. Sad really, but until the American car manufacturers 'get it', thier sales and profits will continue to fall. Cars are too expensive to be buying one based on country loyalty.