Here is some wind tunnel data compiled by Specialized posted on Strava originally by Dave D
Drafting https://www.youtube.com/watch?v=PevpVXelq8A
Shaved Legs https://www.youtube.com/watch?v=DZnrE17Jg3I&sns=fb
Shaved Beard https://www.youtube.com/watch?v=FkmCLOjk2h8
Clothing https://www.youtube.com/watch?v=RmNGQLi36xc
Position on Handlebars https://www.youtube.com/watch?v=9rvJ-6Cgnz8
Helmets https://www.youtube.com/watch?v=bTiyl79dTsg