Making powertrains more efficient is only one part of reducing the environmental impact of vehicles. The energy required to mine and process raw materials into the components that comprise a vehicle and then transport it to the end customer can often amount to a significant fraction of the total energy used to operate the vehicle. In the town of Tabontabon in the Philippines, they have started building new taxis based on renewable materials. The bodywork is made entirely from bamboo. Since bamboo is a grass, it can be harvested and it grows back. It's also extremely strong and lightweight. Of course, this vehicle still won't come close to meeting the crash test standards in North America or Europe but for a low cost, low speed vehicle in a rural area it's a great alternative. Even the fuel is renewable as the engines in these vehicles are fueled by biodiesel produced from coconut oil.