I find that when I'm coasting down a long hill along side carbon fiber bikes also coasting, that my steel bike starts to increase speed over the carbon fiber bikes. I have to keep touching my brake so that I don't put my front wheel into their rear wheel. I don't like constantly touching the brakes down a long slope, so I eventually duck right down with my chin almost touching my stem for more wind resistance and pass a little quicker, to get it over with.
Or is something else going on, like I have less drag from my position in the saddle over them. They have dropped handle bars too, so I don't know. But then again, people with carbon bikes ride the hoods, and down a long hill I'm on the drops. But on the other hand they slam their stem down, and I have mine up somewhat. As you can see, I've been thinking about it, and maybe over thinking it. I don't like passing Cervelo bikes going down a long hill because I feel like their thinking, look at the guy with the old bike, he wants to be a champ and pass us, and the only time he can do that is going down a hill when we're taking a break and coasting.