The subtle intuitions of WRC drivers brought to life in each and every car

We wanted to make a car that would be readily available to ordinary drivers as a commercial vehicle. However, we also wanted to build one with the same high level of precision and balance demanded of race cars used in the extreme world of rally driving. And that is why rally drivers who compete in the WRC participated in the development of the GR Yaris. The result is a car that, in addition to the consistent application of theory and data, has been repeatedly improved and matured based on the unmatched intuition of professional race car drivers. But, it is not easy to incorporate the performance demanded of WRC drivers into tens of thousands of cars in a consistent and uniform manner.

Accordingly, at our plant in Motomachi, Toyota City, Aichi Prefecture, instead of using a regular production line, we built a new dedicated line—the GR Factory— that is capable of achieving the performance we desire in the vehicle’s development. The high-tech line comprises a conveyor-less assembly system consisting of multiple cells and automated guided vehicles (AGV), making highly precise assembly work involving rigid vehicle bodies, which are essential for sports cars, possible. Additionally, the GR Factory also brings together skilled workers from across all Toyota and serves as a place for handing down the expertise and technical capability of the company’s Takumi (master craftsperson) to the next generation. Rather than mass production, the focus of this new line is high-mix low-volume production. With the GR Yaris, we are boldly challenging new ways of manufacturing in search of the ideal.

A gathering place for Toyota’s Takumi (master craftsperson)

Building an even stronger and lighter body

To realize the high-precision high-rigidity body ideal for the GR Yaris, a special structural adhesive is used for the entire body, and the places it is used have been extended by 11 meters. Using a very stiff urethane adhesive for the glue that secures the glass for the windshield and the rear quarter glass has also contributed to achieving high rigidity for the body. Additionally, the distance between welds has been shortened, and the number of spot welds increased by about 200. This process takes several times longer than usual; however, it significantly improves the rigidity of the bond between parts. To reduce weight, a new carbon construction method is used for the roof panel, and aluminum is utilized for the engine hood and all the doors. Also, the front and rear bumpers are significantly lighter due to a new technology that makes them thinner.

Creating the smallest and lightest high-power engine

The heart of the GR Yaris is its engine, and we sought to make it the smallest and lightest of its class. To help achieve this, along with unimaginable power from such a compact engine, we use a hollow camshaft assembly, which is very different from one that uses a conventional casting and machining (cutting) method. To achieve the ideal feel for engine revolutions, we carefully measure the pistons and connecting rods, and by combining parts of equal mass, have realized a pleasing sensation whenever the engine is revved up. During the production process, we thoroughly control foreign substances and manufacture the engine with the same high precision used for racing engines. We also carry out special inspections and tunings according to exacting standards. Based on the assumption that the GR Yaris engine will be used under harsh conditions not normally considered for a regular commercial vehicle, elite, highly skilled mechanics called Takumi build each engine one at a time.

Pursing perfection through precision assembly and tailored inspections

During the assembly process, parts related to steering and stability are subject to three-dimensional measuring. Based on the result, we build the undercarriage with parts combinations and assembly positions that are the closest possible to the target measurements. The body is then attached, with the whole process employing the same high level of precision used when a race car is made. Furthermore, when adjusting alignment during the inspection process, Takumi make adjustments according to stringent standards using equipment that can measure tires without stressing them. In the final step, highly accurate measurements, such as aligning the four wheels while simulating occupants in the car, are carried out on various vehicle specifications. By conducting such customized inspections designed for the GR Yaris alone, we can confirm that the perfection we are aiming for is being achieved as intended.

The final test is conducted by a professional driver on a purpose-built course

After everything, including the body, suspension, and engine assembly processes have been completed and inspected, a final driving test is conducted on a test track. There, a professional driver, using his expertise and own body as a finely tuned sensor, confirms the car’s finish. It is difficult to make judgments based on data alone; thus, it is necessary to discern the feeling a sports car should have using human sense and intuition. From the very start of development, the GR Yaris has been uncompromisingly designed and built through trial and error. Furthermore, on the production line as well, complete commitment to the manufacturing process to a degree unthinkable for a regular commercial vehicle is being made. Thus, with both development and production strongly committed to perfection in this way, an extremely high level of quality is maintained across each and every GR Yaris that is built.

■The photos differ from domestic specifications.
■The photos are for image purposes only.