My 2015 Tucson is making a rattling noise and vibration between 30 -45 mph when coasting and I give it a little gas to maintain speed. It sounds and feels like you are driving over bumps in the road.

What is your question?

I have had it in for service twice at the dealer and the first time they could not find any issues, th second time they told me it was the backseat latch rattling and tightened up thee latch. I still have the issue and I have driven the car with the backseat down to eliminate thee latch as an issue. Since you can feel the vibrations in the floor I am assuming it has something to do with drivetrain or heat shield as others have noted in other reports online.