Oh yeah, the G4500s certainly were terrible vehicles. I think they're a lot better now. The D4505 was a major improvement over the white G4500 when they were introduced, but now the D4505 has gotten worse while the G4500 has been improved, so that the blue G4500 can be considered significantly superior in most ways to the D4505 and the white G4500.
Unfortunately, the D4505 has gotten so bad that now they're right about the same as the white G4500s were. The good D4505s are fine just like the good white G4500s were, but the bad D4505s make me want to puke, the same problem that the bad white G4500s had. The D4505 has had its share of fires, a plethora of breakdowns caused by "regen failure", completely unpredictable suspension, poor trim quality (cracking), and the least comfortable seats Greyhound could have ordered with them.