Cypress - wow, I have an identical issue to yours - word for word the same. I thought it was unbalanced tires, but they just removed my winters and installed summers (newly balanced) and the vibration is back. It happens at highway speeds, and same as you - most pronounced when I leave home and immediately get on the highway, lessens the longer I drive, but never really goes away. Please let me know if you have any success fixing the problem. If exactly the same happens to you and me, I suspect more will follow. (Mine is 2011 LR4 HSE lux)