negation - The reality of answering いいえ to a negative question

tl;dr: when answering a negative question, can いいえ be used to affirm what the question states as a whole?

I came to Japan at the age of six, and I guess I pass as a normal native speaker of Japanese to most people (aside from some personal quirks like long response time).

However, there's one thing, one very basic thing that I have a hard time getting right without a conscious effort: answering negative questions.

Consider this negative question:

車、持ってないんですか？ You don't have a car?

The right way to answer is:

• いいえ、持ってます / いいえ。 Yes, I have one.



• はい、持ってません / はい。 No, I don't.

The problem is, I almost always mix up はい/いいえ and end up answering just like in English. i.e. Describing my situation rather than responding to what the asker has in mind. With a single word answer, with no clarifying comment, it could be a life-or-death mistake.

Over the years, despite the threat of death, I've developed a self-serving hypothesis that with most negative questions, the answer is predetermined and anticipated by context and it doesn't matter much if I screw up. This hypothesis seemed to work sometimes.

My question is, can I keep on believing my hypothesis? For example, if you were asked

もう料理はいらない？

1. Answering はい implies what the asker has in mind "She looks full" is true; your meal is over. (the correct answer in Japanese)


2. Answering いいえ implies you're not in the mood for another dish, just like the asker thought; your meal is over. (according to my hypothesis)

Or, is there no pathway for the kind of logic in #2 in the Japanese way of thinking?

---

Edit 1: to clarify the scope of this question, a few bullet points if I may...

• Assume the question is a simple, plain negative question
  
  
  
  • that is, no double negatives (...じゃないんじゃない?), confirmation in the form of a question (...じゃないですよね?), etc.
  
  
  
  
  


• answered with a single word (はい/いいえ/うん/ううん)


• taking place between true, pure-bred native Japanese speakers

Edit 2: thanks to the feedbacks, I've come up with a definition of the problem in a more formal fashion. Here goes..

Conversations take place amid tensions (or harmony) between several norms:

• Grammatical norm - the correct usage defined by grammar books


• Social norm - accepted, default usage in practice



• Contextual norm - accepted usage defined by context

The question is, when answering a negative question with a single word, can contextual norm disagree with the grammatical one? i.e. can an utterance of "いいえ" mean "はい" as defined in grammatical speak? As of this writing, one answer says yes, two others say no.