2016 Elantra with around 65000 miles on it. Feel vibration around 40 mph and goes away around 50 mph, when accelerating to get to highway speeds. Vibration is felt through steering wheel, but not exclusively. No vibration when slowing down, at idle or other speeds. Although it occurs closer to 55 mph, I had wheels balanced. They were off some and rebalanced, but the vibration still occurs. Tire shop tech noticed CV boot, leaking slightly. So taking to the dealer. I'm thinking if this is where the issue may be, it should still be covered under warranty. Thoughts? ideas?

 

Check your motor mounts.

 

Tire balance possibly , unevenly worn tires, another possibility

 

Don't know if you want to do this, but if you switch the left front tire with the left rear , checked for vibration, if gone that front wheel has a problem. If no change, do the same thing with the other side . If still no change, that will rule out wheels and tires.

 

I've ruled out wheels tire balance, Although I know that occurs. But it typically happens around 50-55 mph. I did however check the tire balance for the sake of elimination and it had not been done for awhile. It was still occurring. I didn't bother checking the motor mounts as I know that could not be the cause. Bad/broken motor mounts would not cause an issue at a certain speed of 40-45 mph, every time, while not happening at slower speeds. I new it would be a rotating part and that centrifugal force would produce a consistent occurrence.
Thanks for everyone's input though.
Update: I just got back from the dealer. Bad axel/CV joint. Part being over-night shipped. covered under warranty. (Yes!!)

 

Thanks for the update! I would've thought there would be some noise while turning, or backing up, I'm glad you found it!

 

I think I caught it early enough. Otherwise, I'm sure it would start producing a noise as it got worse. Thanks