The toyota code was a case of truly abysmal software development methodology. The resultant code they released was so bad that neither NASA, nor Barr, nor Koopman could successfully decipher. (Although Barr posited that the issue was VERY LIKELY in one of a few places with complex multithreaded interactions).

Which therein lies the clue. They wrote software that was simply unmaintainable. Autogenerated code isnt any better.