Thing is, the hybrids have about 3,000 extra pounds on them, and due to the power generation not being that great still, the actual electric motor isn't so strong. If they made them plug-in hybrids (which they bloody should have considering the possibility of a one-time investment saving the MTA millions later on) which could charge at their downtime in the shops off solar cells and hydrogen fuel cells (sewer system hydrogen reclamation systems for this), they could afford to put in a 300+ horsepower electric motor (no transmission to step up, so you're going to want more ponies) with enough torque to spin the earth when the bus moves. They'd also need lithium-ion phosphate batteries placed within the floor Tesla Model S-style. Do all that and you got yourself a hybrid that will massacre a traditional bus on mileage and performance (and cost). In fact, what have these bus manufacturers been doing with their time? They're seriously still putting batteries on the bloody roof.