Hi,
If you feel it the most in the seat and floor, there is a good chance the issue is coming from the rear of the vehicle.
The idea that it gets worse the longer you drive it leads me to think (theory) that it could be related to a brake hanging up. If this happens, it will create heat. The longer you drive, the hotter it will get and can begin to vibrate.
When you notice this, does it change when you apply the brakes? Also, when you get to work tomorrow, walk around the vehicle and take notice if there are any wheels that seem to be putting off more heat that the others. I realize the brakes are new and appear to be fine, but I feel it's worth checking.
Let me know.
Joe
Tuesday, March 28th, 2023 AT 8:08 PM