The 2023 Toyota GR Corolla Morizo is the lightest, strongest, and most efficient car we’ve ever tried. The test results, on the other hand, are surprisingly close to those of the Morizo for a Premium model that is new for 2024 and mechanically similar to lower-end GR Corolla trim levels. A clear reason still needs to be found, even after a lot of research and talking to Toyota. We like a good puzzle, and every year, when we look at performance data for hundreds of cars, we find strange numbers that don’t make sense and make us want to find out more. Tests of a high-performing 2024 Toyota GR Corolla Premium have shown that the test results are more consistent than what we’ve come to expect from Toyota’s competitive three-cylinder hot hatch. Listen to the tense music and picture the mysterious detective holding his hat. A Clear Set of Levels Let’s go back in time to understand things better. The 2023 GR Corolla came in three trim levels: Core, Circuit, and the very limited Morizo. Each trim level had a close-ratio six-speed manual gearbox, all-wheel drive that the driver could adjust, a chassis and suspension that were tuned for performance, and a 1.6-liter turbocharged inline-three engine that made 300 horsepower. The Morizo had different tires for the track (Michelin Pilot Sport Cup 2 Connect) instead of the normal Pilot Sport 4 summer tires. It also had a chassis brace where the back seats used to be, shorter gearing, different suspension tuning, and more torque (295 pound-feet vs. 273). These changes were made in order to lose weight. It also cost a lot at $51,420, and both the front and back Torsen limited-slip differentials were standard on the Circuit but not the Core. The Morizo isn’t available anymore for 2024. In its place, the $41,455 Premium trim, which is mostly better in terms of convenience compared to the $37,635 Core and $46,275 Circuit trims, is offered. Toyota says that all 2024 GR Corollas will get small changes to their aerodynamics and the mounting bolts for their steering hardware and rear suspension. These changes are meant to improve the chassis feel more than the total performance of the car. The Circuit also comes with Torsen differentials and brake cooling ducts, which are also here. Interrupting the Order of Establishment On the test track, the Morizo lived up to its price, performing better than our three different Circuit models from 2023 and 2024. It is expected that the Morizo will be lighter (between 3,185 and 3,252 pounds) and faster (4.4 seconds to 60 mph and 13.0 seconds at 106 mph) when compared to the top cars in that category through the quarter-mile versus the Circuit’s best of 4.8 and 13.3 seconds at 105 mph), grippier (1.02 to 0.97 g), and better at stopping (152- and 301-foot stops as compared to 156 and 312 feet, respectively, at 70 and 100 mph. Now things start to get interesting: Our Premium test car, which is officially the same as the Circuit and weighs 3273 pounds, is the heaviest GR Corolla we’ve tested. However, it matches the Morizo at 60 mph (4.4 seconds) and beats it in the quarter-mile, going 107 mph in 12.9 seconds. As good as its skidpad circle of 1.00 g is its stopping distance, which is 151 feet at 70 mph and 301 feet at 100 mph. This is still true even though it has bigger tires for the street and weighs more because it still has back seats and a rear fan. Things get trickier with the secrets What is it that goes wrong? Finally, Naoyuki Sakamoto, who is the head engineer of the GR Corolla in Japan, needed help figuring out how a car that Morizo didn’t make could be so fast and capable. This suggests that the Premium test car in question is a freak. It’s too bad that more research doesn’t tell much about the subject. To start the GR Corolla, keep the revs at around 6700 rpm and let go of the clutch quickly and smoothly. Using same driving procedures, the same driver evaluated the Premium, Morizo, and one Circuit model on the same course. This takes out a lot of important variables from the equation. At first, we thought that the ambient air temperature—specifically, how sensitive the GR Corolla might be to intake air temperature—might have something to do with it since the Premium was tried at 53 degrees, which was cooler than our previous hot-weather Michigan tests. This line of thinking was made worse by the fact that the GR Corolla’s rear differential has a known problem with getting too hot during long, hard use, which can briefly turn off the all-wheel-drive system. This is something that Toyota knows about, so when it happens, the car tells the driver on the dashboard to stop and let the system cool down. This message showed up for a short time during several Michigan tests, and its arrival and disappearance seemed to be linked to the temperature outside. The Premium isn’t affected by this problem very much. Even though it should make any heat-related problems less likely, we tried a 2023 Circuit model in California, where it was much colder, and it worked as expected, just like previous Circuit models. We don’t know how much of a difference it makes in the GR Corolla because it was using expensive fuel with a rating of 91 octane instead of the 93 octane rating we use in Michigan. But the car’s stopping power and grip were the same as in previous Circuit model tests, which doesn’t explain why the Premium seemed to have better ground adhesion. So, who is it really? The evidence doesn’t support any reasonable explanations for what we’ve seen, so it’s likely that this mystery will stay unsolved. It’s possible that this Premium model was especially skilled. Still, it’s more likely that the car, the road, and the conditions around it all worked together to produce better-than-average results. Our best driver’s car has a feature that makes it stand out. For now, we’ll have to stick with that.
