Something SOUNDS loose, but nothing FEELS loose
 

My 2007 Ion runs very well, and I can feel nothing in the steering wheel or pedals that would cause concern, but quite often, just going over very minor bumps at slow speed, I will hear a "knock" as the tires hit the bump, as if something is loose. It's been happening for quite some time, but there is no irregular tire wear, no pulling or drifting, and my reputable service tech has checked things over and found nothing wrong. But, if that's the case, what could I be hearing? Thanks.

Here's a couple of possibilities from YouTube. I found it helpful when I got my Ion several years ago.

Thank you, Tony!