This vibration issue is getting old and GM needs to freakin figure it out. I have a 2015 with 45,000 miles, been shaking since around 4000 miles. Due to time issues and work I didn't have time to keep taking it to the dealer. Around 9000 miles started hearing what sound like a bad wheel bearing, took it in and found the tires to be feathering / wearing on the inside. which told me the toe is out of adjustment. Then the advisor and service manage advise that is not under warrantly, so much for the 3/36000 mile claim of a warranty HUH. they never adjusted the toe and I just kept driving it and dealing with the vibration and stay either under 70 or above 78 MPH. I finally bought new wheels and tires , vibration still there. I truly believe it's the driveshaft, but haven't the money to spend on getting it replace because I hardly doubt warrantly will PAY for it and I truly don't trust any chevy service center for any honest answers with honest results. SO, do I just continue dealing with the vibration crap or what? Haven't go a clue! I suppose the driveshaft can be condsider part of the drive train, which I'm told is covered for 5 years/ 100,000 miles, but again I don't trust the word of the dealerships. If they can tell me they will replace the shaft under warranty I'll let them replace it, but it will not be replace with the same cheap , poor quality crap made from mexico.
I could always go trade it in for a ford F250, which to me would be the inpardonable sin!