yeah, that's not possible
Its 2800 miles from Phoenix to the southern tip of Maine. To do that in 40 hours would require you to average 70 miles per hour, without stopping. Obviously, much of the trip is in the east, where the speed limit is 65, but more importantly, that's assuming you could drive non-stop. To average 70 miles per hour over that distance, including stops, you'd have to be driving at an average on the road speed well over 80 miles per hour, well over the speed limit in every state.
I think you are making a mistake in your memory, because the math simply doesn't work based on the story you are telling.