Loud noise and vibration at 35mph

[Keith Waits]

I have a 2014 automatic Scion XB. The issue I am having is when my car gets up to 35-45mph, my car makes a terrible grinding/vibration sound. It kinda sounds like driving on the grooved part of the berm. The sound typically only starts when I let off on the gas pedal during that speed range. Sometimes the sound is short lived but other times it carry’s on for several seconds and comes and go’s. The sound only happens in the 35-45mph range. If I start from a stop and accelerate to 50mph and let off on the gas pedal, there is no noise. Unless I continue to coast, then it will start in that speed range. Any ideas as to what it could be? I had a shop look into it and they couldn’t find anything(or replicate it) that was wrong and told me that my car was perfectly safe to drive. I’m a little unsure about their diagnosis and plan to take it to another shop.

My gut tells me that it has something to do with the transmission or that general area.

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