There are several companies including General Motors and Daimler-Benz who manufacture hybrid buses in the USA. These buses do not see much use - few people use public transport across much of the country with the possible exception of the Northeast, I think, and to some extent the larger cities on the West Coast. An old article on MSNBC talks about a 235 bus purchase by the Seattle WA transit authorities: http://www.msnbc.msn.com/id/5075705/ The engines for these buses are made by Caterpillar in Peoria IL and Caterpillar have a strong presence in India. I wonder if our two major bus chassis manufacturers, Tata and Ashok Leyland have even bothered to consider these buses? Cities like the Metros with their huge numbers of buses - Delhi, Mumbai, Chennai and Kolkata must have tens of thousands of city and moffusil buses between them - could save millions of gallons fo diesel if they sed this tech. The MSNBC article talks about a high price for these buses but that could be brought down if these cities began buying these buses in numbers because of the sheer numbers that they would buy. Another opportunity that our people ignore? You bet!
Pakistan runs its buses on CNG because they have large quantities of it and BAngladesh might do that as well because that country sits on some of the world's largest reserves of natural gas. This would, then, be a typical Indian solution but not something that India can afford to ignore. And yet, ignore it is what Indians do!