Some interesting ideas Ron.

However, the Camaro first dates from 1967 - it appears in catalogues that we don't appear to have up on OTD yet.

And I'm not sure what the lead time was on the Monaco, but it was the case supplier Piquerez who approached Heuer with a patented square waterproof case rather than a Heuer-originated idea. It certainly may have been as early as 1967, they were certainly working on what would become the Chronomatic movement by then but it's less likely that the Camaro was some sort of interim model between the Carrera and the not-yet-seen Monaco.

In 1967, I believe Jack Heuer was still working for Heuer in America, before he came back to Switzerland. It's possible he suggested the Camaro name as one that would appeal to that American market and the case shape was simply Heuer getting into the "cushion" case market, which was already popular at the time - Breitling and Rolex, amongst many others, were already offering cushion watches when the Camaro appeared. Its close similarity to the Carrera meant they were able to reuse many parts rather than design everything afresh too, so introducing such a watch was relatively cheap too.

The Carrera dominated Heuer's sales of chronographs through the '60s and most of the '70s, but I don't think the Camaro would really have cannabalised many of the Carrera sales - it was likely Heuer simply cashing in on those people who wanted a watch in the fashionable cushion shaped case.

Whatever the case (why do I always want to use "case" in this sense when I am also writing about watch cases...), the Camaro is an interesting watch and definitely one that deserves some time in the OTD spotlight, with more photos and a table of its own :)