Hi Matthew,
Before I make any more comments, let me say full credit to you for responding to this thread and the comments that have been made. It's never easy to accept criticism, so well done for doing so and noting the points.
Like BDA I have never written a book, mostly because doing so wouldn't interest me but I have been marginally involved on the periphery of one well received Lotus book and I know how much effort went into researching that one and how deadlines slipped. Or rather they didn't slip because the author was fastidious in making sure he had correct detail and all known bases covered. It reminded me of something Chris Foulds (UK Lotus Specialist) used to say when customers complained about the time he was taking - "do you want it quick or do you want it right ?"
I think if you want to produce something that is seen as a reference for the marque, then it's got to be right. Books like the Robinshaw examples on both the Elan and Europa are held in high esteem even though well past their printing because they have loads of detail and, at the time of printing, it was acknowledged as the best source available. But not everyone wants that sort of book and a coffee table book with a general outline and plenty of good photos is equally popular, but again, the details must be right or they detract from the final product.
I accept your points about unnecessary comments on writing style, disagreeing with points you believe are true, etc. Comments on writing style are yours to consider and discard as you wish, it is after all your book. And it's not something open to debate (again, it's your book) so I couldn't see it as a massive time waster, or at least not of your time.
But if someone makes a comment on a detail which you believe to be true, then it's worthy of re-checking because you could easily be wrong or alternatively the critic could have a valid reason for stating his point. Lotus made lots of production line changes, just look at the interior detail changes on the Elans for example.
I've owned Lotus cars since the mid 70s and bought my one-owner Europa in what I took to be totally original condition in the 80s so you'd think I had a reasonable grasp on the Elan & Europa. But there are still things I discover to be either different or conflict with what I was sure to be 100% fact.
It just comes back to what you want to produce; a reference source which will sell well to both knowledgeable and casual enthusiasts, for example the authors Robinshaw, Buckland or Miles Wilkins' books, or a lighter book which is aimed at those who "just want to know a bit about Europas".
As always, your book, your choice. But again, full credit and respect for responding to criticism.
Brian