Looks like the big companies have started thinking green finally. Tata Motors who have already plans to bring Hybrid Nano for fuel efficiency is testing buses and light trucks which are driven by hydrogen powered cell fuels which means zero pollution to environment.
The basic chemistry involved here is that when you burn hydrogen with air you get water as by-product instead of polluted air and hence one can even think of using that water to cool engines or any where else.
Well it might just take some little time for you and me to see these bus and trucks running around but as Tata is working with ISRO closely on this we might see it soon. Lets hope for green future.