Sonatas with the 2.4 engine have quite a lot of vibration when the car is
in gear. This is, unfortunately, inherent in their design and will never
Since you say the vibration has gotten worse since about 27,000 miles,
it's possible that you have an issue with the motor mounts. If that's the
case, replacing them will reduce (but not eliminate) the vibration.
You could call Hyundai customer assistance, but I'm thinking that won't
get you very far unless you meet with the factory rep and are absolutely
adamant that the vibration is significantly worse than before.
If you're game, call the service manager and offer that you won't bring
the issue up again if they replace both upper mounts (one engine mount
onthe right side of the vehicle, and one transmission mount on the left).
Of course, this means that if nothing changes, you'll need to keep your
word that you won't bring it up again. But in that case, I'm suspecting
that the vibration is indeed normal, as they say.