Even though they look alike the roof rails on the Q5 and e-tron are generally different sizes and shapes especially considering the e-tron's special design for aerodynamics. That means just swapping them over probably won't work. If you ever manage to attach them, you'd likely have problems with them fitting correctly, staying secure, and even making extra wind noise. You;ll most likely need roof racks made specifically for the e-tron to avoid any problems.