Toyota has adopted a concept known as "sustainable mobility."
We are seeking to create a mobile unit with sustainable mobility at the core; in other words, the ultimate "eco-car" that allows the Earth, people, and vehicles to coexist harmoniously long into the future.
To achieve this, we are developing technologies from the following three perspectives to enhance the environmental performance of vehicles: 
The vehicle must not only have outstanding environmental performance, but also be able to exhibit this performance anywhere in the world, no matter what the environment, lifestyle habits, or economic conditions.
One example is fuel. The ultimate system must be able to operate on gasoline, bio-ethanol, or hydrogen. And Toyota's hybrid system will make that sort of flexibility possible.
A short trip to a local convenience store, to take one example, would be perfect for a one-person personal mobility unit that operates solely on electricity or a small two-person commuter vehicle.
Meanwhile, the appropriate vehicle for going out on a drive for pleasure would be a hybrid or plug-in hybrid vehicle, which can travel a relatively long distance carrying multiple passengers without having to be charged and which can travel using the existing infrastructure.
A fuel cell hybrid vehicle would be ideal for large and commercial vehicles that are used frequently and driven long distances.
By choosing the vehicle that best suits the driving situation, in that sort of way, vehicles can become more environmentally considerate.
We can minimize the energy used for transporting people and goods by providing the most appropriate vehicle for the given situation and time.
This is Toyota's concept of being environmentally considerate, based on the right vehicle for the right place at the right time.
Source: http://www.toyota.co.jp/en/tech/hybrid/hybrid/index.html