With a 7PM departure, do not even bother trying to take a car - you will get stuck in the loads of outbound traffic during rush hour. As others have suggested, get to Penn Station and take NJ Transit. If you have a lot of luggage, I would also suggest earlier as well given how packed the trains are - or, to let you in on a secret - line up for NJT not by the 7th Avenue side of the train station but instead on the Amtrak side, where it is much easier to access the same tracks via the middle stairwell (and also put you on the front of the train, which leaves you closer to the escalators going upstairs at the EWR train stop).