This vehicle experienced a sudden engine failure while traveling on the highway which caused an immediate loss of power. The safety of myself and my family was at risk as we exited the roadway to the shoulder without power and the vehicle shaking violently. Vehicle was towed to a dealership where upon inspection they found the rocker arm for the intake valve on cylinder 6 not moving, a bent pushrod, and a lifter that had come apart. It is unknown if an inspection was performed by the dealer beyond the initial diagnostic. The check engine light had come on within the last 12 hours. We called onstar and they said the code indicated we should bring the car to the dealer within the next 24 hours. There was no indication that it was unsafe to drive with the light on.