Nobody has been able to fix this or even tell me what it is, I have had several mechanics look at it. Started off by balancing the wheels, that wasnt it. Rotated them as well, also not it, bought new rings for the aftermarket rims, that wasn't it. Bought new rims when we found out the aftermarket ones weren't seated right. Nobody can tell me why this car shakes on the highway. I drive almost exclusively on the highway so this is very annoying for me.