what would cause the vehicle to shut down down driving on the highway?
Loss of fuel, loss of spark, alternator failure, ignition switch failure, crank sensor failure. Lot’s of things. To narrow things down you need to give us more info. Does it crank? Was the check engine light on? Do the headlights turn on? Can you hear the fuel pump turn on for a couple of seconds when you turn the key to the on position? Give us something to go with.