Don't know... I've read sometime the core temps of these kids remains above 107 108 for hours after. But to answer you question in honestly have no clue. But I can pick my child up from school or camp and tell she had been sweaty if even she isn't anymore. The amount of sweat he released I think would still be evident In my opinion
But bodies don't sweat after they are deceased.
Tomorrow morning at 9:00, it's expected to be 74 in Atlanta. It was hotter the day Cooper died. Let's just use tomorrow as an example, though. I am using the table at the link, because that's the one I have bookmarked. (If you google search it's the same as other tables, just for reference!) If it were 70 degrees at 9:00 am, in one hour it was 113 degrees. It was 91 by noon, so the temps rose pretty quickly. I think Cooper had been deceased MOST of the 7 hours he was in that car. I don't think it's possible for him to have been soaking wet, unless someone wet him down. He wouldn't have sweat for hours.
http://sites.tufts.edu/jumble/2013/06/03/its-heating-up/