In the early 1990s, Toyota saw that environmental concerns and stricter emissions regulations would determine the future of the automotive industry. The company’s goal was to create an ecological, efficient vehicle that would meet future standards.
In 1997, Toyota introduced the Prius to the Japanese market. The car was the world’s first mass-produced hybrid vehicle to combine gasoline and electric power to reduce fuel consumption and emissions. His worldwide debut came in 2000.
The development of the Prius presented significant technical and market challenges that included designing an efficient hybrid powertrain, managing battery technology, and overcoming consumer skepticism about combining an electric propulsion system with a standard gasoline engine. But Toyota persevered, and its instincts proved prescient and transformative.
“The Prius is not only the world’s first mass-produced hybrid car, but its technical and commercial success has also spurred other automakers to accelerate the development of hybrid vehicles,” says IEEE member Nobuo Kawaguchi, a professor in the Department of Computer Science and Engineering at Nagoya University. Graduate School of Engineering in Japan. He is also the secretary of IEEE Nagoya Section. “The Prius helped shape the role of hybrid cars in today’s automotive market.”
The Prius was awarded the IEEE Milestone on October 30 during a ceremony at the company’s headquarters in Toyota City, Japan.
Project G21
Development of the Prius began in 1993 with the G21 project, which focused on fuel economy, low emissions and affordability. According to a Toyota article detailing the project’s history, by 1997 Toyota engineers—including Takeshi Uchiyamada, who has since become known as the “Father of the Prius”—were satisfied that they had accomplished the task of meeting all three goals.
The first generation Prius featured a compact design with aerodynamic efficiency. Its breakthrough hybrid system allowed seamless transitions between an electric motor powered by a nickel-metal hydride battery and an internal combustion engine powered by gasoline.
The car’s design included regenerative braking in the powertrain layout to increase the vehicle’s energy efficiency. Regenerative braking captures kinetic energy that is usually lost as heat when conventional brake pads stop the wheels through friction. Instead, the electric motor switches to generator mode, so the wheels drive the motor in reverse rather than the motor driving the wheels. Using the engine as a generator slows the car down and converts kinetic energy into an electrical charge directed into the battery to recharge it.
“The Prius is not only the world’s first mass-produced hybrid car, but its technical and commercial success has prompted other car manufacturers to accelerate the development of hybrid vehicles.” —Nobuo Kawaguchi, IEEE Nagoya Section Secretary
According to Toyota’s article “Harnessing Efficiency: A Deep Dive Into Hybrid Technology,” the breakthrough was Hybrid Synergy Drive, a system that allows the Prius to operate in different modes—electric only, gasoline only, or a combination—depending on driving conditions.
A key component that Toyota’s engineers developed from scratch was the power-split device, a planetary gear system that allows smooth transitions between electric and gasoline power, allowing the engine and motor to power the vehicle in their respective optimal power ranges. The arrangement helps to optimize fuel consumption and simplifies the drive train as a traditional gearbox is not required.
Setting fuel consumption records
Almost 30 years after its commercial debut, the Prius remains an icon of environmental responsibility combined with technical innovation. It still sets records in fuel consumption. When the newly launched Prius LE 2024 was driven from Los Angeles to New York in July 2023, it consumed a paltry 2.52 liters of gasoline per 100 kilometers during the 5,150 km cross-country drive. The record was set by a so-called hypermiler, a driver practicing advanced driving techniques aimed at optimizing fuel consumption. Hypermilers accelerate smoothly and avoid hard braking. It lets off the gas early so the car can coast to a slow stop without using the brakes, and drives as often as possible between 72 and 105 km/h, the speeds at which the car is usually most efficient.
A driver who does not use these techniques can expect a fuel consumption of up to 4.06 liters per 100 km in the latest generation of Prius models.
Toyota has improved the Prius’ hybrid technology with each generation, cementing the car’s role as a leader in fuel economy and sustainability.
The Milestone event attracts notable personalities
At the IEEE Milestone event, Uchiyamada spoke briefly about the Prius development process and the challenges he faced as G21’s chief engineer. Other notable attendees included Takeshi Uehara, president of Toyota Powertrain; Toshio Fukuda, IEEE 2020 President; Isao Shirakawa, Chairman of the IEEE Japan Council History Committee; and Jun Sato, Chairman of the IEEE Nagoya Section.
A plaque recognizing the technology is located at the entrance to the Toyota Technical Center, which is within walking distance of the company’s headquarters. reads:
“In 1997, Toyota Motor Corporation developed the world’s first mass-produced hybrid car, the Toyota Prius, which used both an internal combustion engine and two electric motors. This vehicle achieves revolutionary fuel efficiency by recuperating and reusing energy previously lost while driving. Its success helped popularize hybrid vehicles internationally, advanced the technology necessary for electric drives and contributed to the reduction of CO emissions2 emissions and influenced the design of subsequent electrified vehicles.
Administered by the IEEE History Center and supported by donors, the Milestone Program recognizes outstanding technical developments worldwide. The nomination was sponsored by the IEEE Nagoya Section.
