2014 Hyundai Elantra steering problems

On 5/30/14 I purchased a 2013 hyundai elantra close out with 54 miles on it. At 4300 miles I lost all control of the steering and the car went across 3 lanes of interstate 3 times before I regained control of the car. I returned the car to the dealer and had to "trade it in" to get a different car. I left the dealer with a 2014 elantra limited on 7/21/14 having to pay them an $4500 extra.

While driving at highway speeds, the rear of the 2014 elantra consistently sways and at times causes vehicle to actually drift into other lanes which is a huge safety issue to me and my family, my fiancee is actually fearful of driving this car as I am. We have had the car back at dealer and have been told it's the way the car is made. I actually spoke on phone with hyundai motors eastern seaboard district manager [xxx] ( his phone number is [xxx] )and claims he has never heard of the swaying issue.