The driving metaphor comes from the contrast between (effectively) renting a BMW motorcycle (since they are hard to repair), and owning a simpler model that can be maintained by oneself.
The stated benefit is greater autonomy and satisfaction derived through taking ownership and solving one's own problems - a more classical approach to life. Rather than taking a "fix this for me" attitude, you see the world as something that you have control over.
Personally, I've found it very satisfying every time I'm able to repair something in my car, which I've owned for 8 years.