I am surprised by the other comments - I have been upgraded (including BA and Air Canada) with a special meal ordered (lacto-ovo vegetarian is my default). Perhaps it is because there is usually a veggie option as part of the main meal service (but might not be a low sodium, or diabetic type meal), but on at least two flights they have brought me my Y meal to the front as well (and on one occasion I ate it, along with the salad course, cheese course and pud that everyone else was having, on the other I declined and asked for the pasta that was veggie instead). Maybe it depends what your special meal is as to whether it affects your chances?

I've also been offered the AC upgrade at check in online options, although it is a long time since I flew Air France, so can't comment on them.