Toyota Corolla GR (GZEA14H)

Early in development, the car was tested with the same engine as the GR Yaris. But the drivers taking part in development said it "has no power," and President Toyoda himself halted development, saying, "This won't do. Think from zero." Sakamoto believed that getting more output would mean rebuilding a 2.0-liter turbo, adding years to development. The one who offered a hand was the chief engineer for engine development, who had also worked on the hydrogen Corolla. The GR Yaris running in Super Taikyu was already making 304 PS and 400 Nm, and the team knew which parts would break in mass production, so the car could be given the 304 PS engine.

Like the GR Yaris, the GR Corolla is built at the GR Factory, the line dedicated to GR cars at the Motomachi plant. Every part varies a little (its tolerance), and pairing a part that is -3 from spec with one that is +3 brings the tolerance to zero. According to Sakamoto, to get the intended performance exactly as designed, each part is measured and AI instantly optimizes how they are combined. Not a single part is thrown away.

Ishiura went beyond being an evaluation and development driver: midway through development he also attended the meeting that decides whether a car goes into production, and gave his frank opinions. According to Ishiura, before the GR Yaris his job was to drive a car that was already largely finished and convey its appeal and character. With the GR Yaris and GR Corolla, he joined at the planning stage, before the first prototype was built, and the work changed to building the car together to make it appealing.