You could also fly, and take a nap there... The biggest benefit to a road trip is flexibility. If you see something that catches your eye and want to look around and take some pictures, a train doesn't give you that. If you decide to stay an extra day somewhere, the effect on your budget could be significant for other forms of travel.

As for pollution, maybe if they were building more nuclear plants and high speed chargers, then electric vehicles would actually be a better option for longer distance travel. Of course not counting the environmental impact of building a bunch of new vehicles vs. the one that I've had for over 7 years.