The vibration is in the steering wheel and in the floor, so I don't think it's related to steering. It is not related to engine RPMs, but the frequency is related to vehicle speed (and no, I'm not driving with the massaging seats on). The issue is particularly noticeable when driving on a smooth road surface (obviously). And since I drove my 2013 on the same road without issue, I know it's not the road itself that's causing the issue.
Thanks to those who replied stating that you're not having an issue. If anyone else has noticed the same issue, I'd like to hear about it. There are other posts on the forum that allude to this problem, but those discussions tended to blame tires. Since I've done all of the tire diagnostics, including replacing them even though the car is brand new, I thought it would be best to get a separate discussion going to see if others have ended up where I am, which is frustrated.
As I said, I'll try driving a Sport and a 2WD limited soon and will see how they compare.