Is there one way? Is the teacher-student model the best way?

For example, I want to learn about cars. Specifically, I want to have some general idea of how the thing works and what the fuck I'm even looking at when I open the hood of my car. It looks like a jumbled mess of metal and shit thrown everywhere, it's not at all clear to me what anything is or what it does or why it exists.

What is the best way for me to figure out what the fuck is going on? Is the best way to learn about what's going on under the hood of a car the same approach that you would take to learn calculus? Or are there different approaches depending on the subject? And are there individual variances?

How much does IQ matter? Within normal ranges, is IQ just a way to increase the rate at which you learn? Or does having a low IQ preclude you from learning certain things? And how do you know this? How does anyone know anything at all?