So, this happens consistently .. at hwy speed, some vibration in steering wheel which also felt by my feet (on gas pedal, etc). If I then brake hard, the vibration subsequently all but disappears.

I am discounting unbalanced wheels (the vibe shouldn't go away if that were the case, right?)

Had dealer check for loose front end/steering rack last time in for service, they found nothing.

Any thoughts?

TIA