I thought the trailer was about 1 ton heavier for the Chevy as well, since it was a "Super Ike" test.
I'd have to go back and watch them again, but I thought the Ford and Dodge trailers were just over 14,000 lbs, and the Chevy a bit over 16,000 lbs.
If that is correct, that would definitely skew the results in doing direct comparisons. But definitely fits the theme of the "Super Ike" test.
I like the way they do the testing, as it represents kind of a "worse case" scenario.
Edit to add:
went back to watch the videos.
Ford and Chevy same weight, same trailer. Only real difference was Ford was run on a very cold clear winter day, where Chevy was a warmer spring day. So air density, would slightly influence to the Fords favor (not three minutes worth... lol)
Dodge pulled a 14,300lbs trailer with a clean roof, so not comparable (imo).