Vibration/buzzing noise
I have also noticed some buzzing at high speed coming from somewhere upfront, but I don't think the floorboards are the culprit. I can't find anything loose and made sure my keys weren't banging around. I thought maybe it was the left mirror, but it continues even when I hold it. It is a very minor issue, and anytime you are paying attention or listening for a 'noise', you tend to hear things you normally tune out. I wonder if it's the flap over the battery compartment or one of the sensor wires vibrating in the wind? Because it's so minor, intermittent, and you have to pay close attention to hear it, I simply ignore it. I would, however, be interested in knowing its cause.