mine also has the slight knocking coming from the front wheels paired with a loose feeling the steering wheel when traveling over imperfections on the road... i still have that 30-day carmax guarantee so i'll know what to suggest when i take it there...

 

I had the same problem with my max. Replaced all 4 struts and bearings and still doing the same thing up front. Figured I would have to do ball joints or mounts at some point. Then, about a month later I was changing my starter (which means you have to remove most of the airbox) and found that a piece of the pre-filter airbox plumbing (a mysterious white plastic reservoir looking item) had had one of its screws come loose. The part had been bouncing around out of sight inside the bay. Point is, assess YOUR car and don't neccessarily get too focused on big stuff.

 

Worn bushings are the culprit...but which ones?

Get CARMAX to do a front end alignment and have the mechanic check the the CV joints, tie-rods & steering knucles, sway bar links, and control arms. If these are all OK -- which I doubt -- then have him check the steering gear.

 

I replaced the stabilizer bar bushings on my 5th Gen SE and the problem of the "loose steering wheel" feel went away. I got the 23mm OEM stabilizer bushings from the Nissan dealer for $13. That loose feel was very annoying because it felt like the steering wheel was guiding the hands, not the other way around. I replace the stabilizer end links a while back and noticed that some noise went away as well. But I still get a "dropping" noise when I go over deeper bumps, I have a feeling it's the strut mounts, because they weren't changed when I replaced all 4 struts, so I know they're old.

Hope this helps.