Above about 30mph I get a slight vibration in the steering wheel, almost a buzzing feeling, and I can hear it if I turn the radio off and the road is smooth. The steering doesn't pull in either direction, no unusual tire wear, alignment was done right after I bought it in November. It seems to go away if I step on the brakes, but it could just be my head making it seem that way. From browsing the forum I've learned (assuming I didn't misunderstand) that the brakes can get build up that can make the brakes shudder, and I'm kinda wondering if maybe I have a pad dragging on the rotor a little bit. Anybody else had this happen?

 

Jack up each end and turn the wheels by hand, you'll know immediately if it's a dragging pad.

My typical check for any potential brake related issues is to get up to highway speed on an empty road and stand on the brakes, I usually try to chatter the antilocks just to make sure I went 100%. If it feels normal it's probably normal, usually if there's a problem you know IMMEDIATELY when you're on the brakes hard like that.

 

Almost 100% that it's a dragging pad. I drove to work and once i parked I ran inside and grabbed a temp gun from my shop, ran back out and checked caliper temps. Left front and both rear calipers were in the 55-58* range, right front was 72*.

 

Problem solved, changed the brakes out today and went for a drive in the country to bed them in. Vibration was still there, didn't sound any different from before. However, with all the turns I got to take at a speed where the vibration was easily felt,I noticed that it was much more obvious when taking left turns, and almost non-existent when taking right turns. So now I'm looking at getting new front wheel bearings, primarily the right side.

 

I just had this same problem; unusual noise/vibration, car didn't accelerate as normal. I jacked it up and checked for bearing wear and driveline noises - nothing.
Then I took my G35xS out on an interstate run, came back on secondary street. I could feel "pulsing" every time I stepped on the brakes.
Got it home and felt every wheel; left rear wheel was hot to the touch. Replaced both rear brake calipers, pads and upgraded to slotted rotors.
No more noise, or drag; wheel was cool to the touch - it was a seizing brake caliper. It was affecting my gas mileage as well. Be careful when you touch-test the wheels; some calipers seize so hard, the wheel can burn you.

 

Replaced both front hubs yesterday and enjoyed a nice quiet, smooth ride to work this morning. Teardown didn't take too long, once I confirmed that the number of splines was correct on the new hubs I pulld the old ones out with a slide hammer, took about 5 minutes per hub. Relatively quick and easy to do in the garage.