Earlier quoted context omitted.
Following your metaphor of the PT Cruiser: it seems like they followed a waterfall process. They came up with a list and then built a car that fulfilled that list without evaluating what they were building st every step along the way. If they'd done it agile-ly, the crappyness may have surfaced much earlier in the development of the car... Maybe early enough to have done something about it. Alas, agile doesn't really…
Agile doesn't work with cars because you can't deliver value incrementally by designing additional features. Producing a brake pad this week doesn't help if the chassis is still unfinished. Similarly having the entire car except the brake pads complete doesn't deliver any value. It's all or nothing.
"As a driver, I can stop the car at a reasonable pace" - ok, maybe you get some awful brake pads to begin with (or maybe if you are cheeky you just say...well, air resistance does that!)
"As a driver, when the car is travelling fast, I can stop the car extremely quickly" - ok so now we probably need some reasonable brake pads.
"As a driver, I don't need to replace the stopping mechanism all the time" - ok so maybe now we need to make sure the brake pads fitted are of a certain quality.
I think you can see where this is going. Sure the car probably needs brake pads...but assuming you didn't know much about cars (something agile is suited for), at each stage you could decide you need to do something different for the stopping mechanism. Additionally, many of the qualities of the brake pads demonstrate that things are not "all or nothing" necessarily.