Oh yeah, I think I might know the fourth icon on the D4500CT's door. Anyone think it's for Greyhound BLUE, the new entertainment system? Those buses are based from Boston Garage, a highly-competitive area. Whether it's running, Boston-New York, Boston-Cleveland, Boston-Montreal, or Boston-Bangor, there's a lot of competition, and Greyhound might be trying out BLUE in that area to gain ridership further.
What's interesting is that Greyhound has not lost any ridership against Megabus, right now it's merely a fight to grab new passengers, and Greyhound is trying to gain the upper hand with those long-haul Limiteds that Megabus can't cover. Looks to be working and the Greyhound LDs and ULDs are growing like crazy. Greyhound execs say the whole network will have Express and Limited service by 2016 (excluding Greyhound Connect and the rural routes), I think that would include New York-Los Angeles.