The dealer said it is but could not answer me if the antenna was in place under the what looks like (a mini fish fin) on the roof, by the rear window.
I want to add XM, but do not want another external (black) xm antenna mounted on the car... Im hoping its in place under the color coordinated lil fish fin
Thanks!

 

generally lexus models are not prewired for any accesories other than what is ordered. toyota started prewiring on some 2005 models for the first time but no sign that lexus is doing the same.