Humming Sound
 

I have notice the 2011 Elantra makes a struggling sound when the car is turn on and when the gas is press on. The car makes a loud noise as if to say it is stuck in snow or climbing a hill. Is this problem normal on all the 2011 Elantras? This question is mainly for those living in the US or acquainted with the system here. Is it possible to buy a navigator on the Elantras that don't come with it?