Uchiyamada proved to be a creative leader, yet very focused on achieving aggressive timing targets. In fact, the more detailed conceptual blueprint was completed in just six months. Normally the first step in this phase would have been to develop a physical prototype. But Uchiyamada decided that if they quickly made a prototype they would get mired in the details of improving it. He wanted to thoroughly discuss multiple alternatives before narrowing in on a decision. My associates and I have termed this “set-based concurrent engineering”(discussed further in Make Decisions Slowly by Consensus) , in which sets of alternatives are broadly considered rather then focusing in on a single solution.There were many examples of this set-based thinking throughout the Prius development.
In the early stages, the team was quickly bogged down in discussing technical details of power-train technology. Uchiyamada saw this as a problem. He called the team together and said, “Let’s stop this. Let’s stop focusing on hardware. We engineers tend to focus on hardware. However, what we need to do with this car is to focus on the ‘soft’ aspects, not the hardware. Let’s forget everything about hardware and review from the beginning the concept of the car that we are trying to build from the ground up” (Itazaki, 1999). Uchiyamada then lead a brainstorming session of key concepts to describe characteristics of the 21st-century car. Several days later, after many keywords had been generated and discussed, they reduced the list to two key words that ended up driving all subsequent development: “natural resources” and “environment.”
Automobiles account for about 20 percent of the carbon dioxide from all human sources, yet about one fourth of the world’s population enjoys their benefits. The goal for the G21 was stated as a “small, fuel-efficient car.” Ultimately, a hybrid engine was the key to the solution. An electric vehicle certainly would have been fuel-efficient and would have produced almost zero emissions, but it was not considered practical or convenient. You need a separate infrastructure to recharge the batteries, the distance between charges is short with the known technology, and the batteries that have the needed power are huge. The car would be a “battery carrier.” Fuel cell technology, on the other hand, had great promise, but the technology was not nearly developed to the point of being viable and was possibly decades off.
Hybrid technology had a nice blend of fuel economy, low emissions, and practicality. The basic idea is to let the gas engine do what it does well and the battery-driven motor do what it does well, thus recapturing as much as possible the energy generated during driving and braking. Internal combustion engines are not very efficient at acceleration but are very efficient once a certain rpm level is reached. Electric motors are much more efficient at rapid acceleration. When gas engines are running, they can then recharge the batteries, so there is a harmony between the gas engine and the electric motor. In the most sophisticated hybrids, computers determine which of the two engines is most efficient, based on speed, road grade, number of passengers, and other variables. Even the energy used in braking can be recovered as electrical energy.