The Secret to the Toyota GR Corolla's Success? Cooling
We talk to Chief Engineer Naoyuki Sakamoto about what makes the GR Corolla's new automatic transmission work.
For years, Americans salivated over the GR Yaris. We watched lustfully as Toyota's feisty three-door drifted its way into the hearts of our European brethren, teasing us from afar with its punchy turbocharged engine and angry-yet-adorable looks. Forbidden fruit to the highest degree.
Unfortunately, we'd never see the Yaris Stateside. Toyota said it simply wasn't the right car for the job. But in 2023, the company debuted the GR Corolla hatchback, a mechanically identical counterpart to the GR Yaris—only bigger. And with that, the Yaris was all but in our rearview.
Fast forward two years, and the GR Corolla is a certified hit. It's one of the last great hot hatchbacks in the US, and by all accounts, nearly as feisty as its Yaris cousin. Take that, Europe.
This year, Toyota reaffirmed its commitment to the GR Corolla by broadening its appeal with an automatic transmission. But before you boo and hiss—this is no off-the-shelf auto.
GR Corolla Chief Engineer Naoyuki Sakamoto has been with the project from the beginning. Standing trackside at Eagles Canyon Raceway in Texas, he tells me exactly what makes this transmission so special—and how they managed to fit it in the GR Corolla.
"That automatic transmission was developed through motorsport activities," says Sakamoto. "We took that transmission to the GR Yaris in Japan, we joined the Japanese rally championship series… Then, we identified any problems in motorsport racing conditions. After that, we decided to apply that automatic transmission to the GR Yaris."
The eight-speed, Direct Automatic Transmission went from the rally stage to the GR Yaris, and eventually to the GR Corolla. The gearbox is tuned specifically for high-performance driving and, in the case of the Corolla, engineered to handle more torque. The GR ‘Rolla now makes 295 pound-feet this year as opposed to 273 from last year.
'The automatic transmission was developed through motorsport activities.'
It isn't just a copy-and-paste job, either. While the case itself is identical to the Yaris's, virtually everything else about the transmission is unique. The Corolla has shorter gear ratios, new friction materials for the clutches, and a new valve body for faster inputs. Hell, it even has dedicated programming for the automatic mode. Sakamoto goes more in-depth on the new transmission in a previous interview with Motor1.
With an additional 28 horsepower over its European cousin, and now more torque than last year, giving the Corolla an automatic wasn't as simple as bolting in the new transmission and calling it a day. Toyota engineers needed to make a few key changes to the GR ‘Rolla for 2025; one of the biggest areas of focus being cooling.
"We needed extra cooling for the automatic transmission," Sakamoto tells me, pointing to either side of the vehicle’s grille. "We added an additional radiator… The automatic transmission has air cooling and water cooling. The engine water gets [hot]... so we needed additional radiator cooling."
"The original GR Yaris made 272 horsepower," he continues, "the GR Corolla gets up to 300 horsepower. So, to increase that [number], we increased the engine parts and put in an additional cooling system."
'We needed extra cooling for the automatic transmission.'
Toyota doesn’t have any specific measurements on how much larger the 2025 GR Corolla’s grille is compared to 2024—but it’s obvious just by looking at it. The former fog lights are gone (much to the chagrin of some enthusiasts), and now two larger vents feed fresh air into the engine bay—particularly, the new radiator.
When I ask Sakamoto how much more power this engine and transmission could theoretically handle, he laughs: "Difficult question."
"We tried to increase engine power with the TCR Corolla [race car], then we broke [it]," Sakamoto says. "We know the limit, we know how to increase the engine power. But still we are studying. We are always trying to push the limit…"
"Hopefully, we can come to a measure to increase power," he says, "and eventually, with that planning, it can come to the production Corolla and GR Yaris."
The good news is that if you’re allergic to automatic transmissions, the six-speed manual still exists. And it’s still superb. But if you’re going to put an automatic in one of your most beloved performance cars, you better do it right.
Toyota, thankfully, nailed this one.
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