Anyone could measure it; you too if you have an Element. It is easy to pry the covers off with a smooth screwdriver tip.
I don't know the exact side to side spacing, but do know that 48" Yakima cross bars work with an inch or two to spare.
Front to back, it is close to 27" if you center the rack on the 3 mounting holes. But the Yakima mounts only use 2 of those holes, so the spacing between Yakima bars is closer to 28-29".
Those numbers give you a rough idea. Beyond that you'll have to measure for yourself.
If you want further help, be more specific as to why you want to know.