There is not factory antenna in the hardtop cars... but you can certainly add an antenna and it will work. I did it to my 2016 hardtop car (which has the premium audio) and I had the service center enable the XM when i did MC2 upgrade.
In detail there is a harness installed with Fakra K Curry connectors but no antenna. You can remove lower left (driver) trim and see the antenna connector. Need to connect and antenna to this. (see picture) Can google "fakra k satellite radio antenna" for options, they are not expensive.
Another pro tip, you can get OK performance by locating the antenna on the dash or something, but it will work best if you can locate on the roof of the car. I managed to route mine through all the trim/headliner and out the top seam of the hatch (just need to tape down carefully to not pinch) , and then used another magnet (between headliner and roof underside) to couple to magnet on antenna (since roof is aluminum this is needed)
-Tom
