Upon picking up speed a vibration or rattling or road echo seems to come from the undercarriage. Is that ok?
that doesn’t really narrow down the problem for us to answer.
A vibration can be caused by an out of balance wheel, a bad motor or transmission mount, exhaust hitting the underside of the floorboards. to name a few.
A rattle can be from loose exhaust, loose heat shield, ect.
you should bring it to a reliable repair shop to have it looked at.
Just to add to what Warrior posted… and none of this is OK!