Malibu started having a vibration problem at 400 miles. Tires were balanced by Dealer but problem continued. Tires were “forced balanced” at GM expense at independent tire store and two of the tires were found defective. Two tires replaced by GM. Helped. Now at 60-80+ mph (Thruway) vibrations intense in steering wheel, driver’s seat, my legs to my knees. Could this problem be more than tires out of balance? Now 2200 miles on car.
It’s possible. A trip to your local alignment shop for a full inspection is in order. The vehicle could have struck something on the highway or a deep rut in the road. Anything is possible. It’s better to be safe than sorry. Keep all documentation just in case matters get worse. If you have to see the GM Zone manager in the future it’s best to be prepared.
It is possible that you have a defective steering rack.
I have seen this exact problem on new or nearly new cars, and it was due to a steering rack that was slightly “out of spec”.