Chicago is going to evaluate a new type of hybrid bus. Their press release sounds as though there could be a very significant fuel savings CTA | Chicago Transit Authority - CTA Press Releases Norm
that is exactly what i said earlier; that other types of more fuel efficient engines besides ICE (that is only aboround 25 % efficient) could be used with hybrid vehicles, and that using a separate engine to charge the batteies is lot better option than paralel hybrids. A turbine engine is lot more fuel efficient and it is lot smaller, for output power. add to this mix regen braking and solar panels on roof and you could get your bus MPG up in low 10s.
