okay, I actually just tried it. Works for me:

user=> ($map (fn [s] (/ s)) :speed cars)
(1/4 1/4 1/7 1/7 1/8 1/9 1/10 1/10 1/10 1/11 1/11 1/12 1/12 1/12 1/12 1/13 1/13 1/13 1/13 1/14 1/14 1/14 1/14 1/15 1/15 1/15 1/16 1/16 1/17 1/17 1/17 1/18 1/18 1/18 1/18 1/19 1/19 1/19 1/20 1/20 1/20 1/20 1/20 1/22 1/23 1/24 1/24 1/24 1/24 1/25) 

via lein try incanter