Leave it to Ford to build interesting products that they can't fix very well...
My 2001 Focus 5spd started to have a humming/buzz come from the front when you went over a dip. Not suspension noise, did it with the clutch in or out. Then in turning to the right, you would get the same humming/buzz, but it was relative to the wheel speed and it got louder and then quieter with the rotation of the wheel. Sort of a wuh, wuh, wuh... that sped up with the wheel speed.
Anyways, the SECOND time I took it in to the Ford dealer, they had it for three days and had to call the Ford engineers. The problem? A bad motor mount. They replaced it and it was almost like driving with ear muffs on.
It's now at 74K miles, stays around 32-36 MPG, and other than the dorky "shark-fin" radio antenna, looks fairly modern.