The wave of electrification promised that such engines were on the verge of extinction. But the announcement that Toyota, Mazda, and Subaru are designing a new generation of engines of this type makes sense, as there is a future that combines new combustion mechanics with electric propulsion support, known as hybridization. Total electrification has proven to be less viable than futurists imagined. While many manufacturers have fully embraced it, others are showing some resistance. Tradition? Maybe not. The fact is that hybrids have many advantages, perhaps the biggest being the ability to run without the need for recharging, which applies to both conventional (parallel) and plug-in vehicles. The collaboration between companies aims to use more renewable fuels, as well as the common goal of carbon neutrality throughout the production stages, a target that is challenging for many electric vehicles. Toyota has a tradition of investing in various mobility solutions, indicating that electric and hybrid vehicles can be explored in parallel. “It is crucial to consider the needs of consumers, infrastructure, and explore options that meet the local context. Among them, vehicles that combine electrification and combustion engines,” says Roberto Braun, communication director of Toyota Brazil. Even though the partnership announcement was made some time ago, only now have the manufacturers talked more about their projects and shown prototypes of the engines, as well as individualized plans according to each company’s tradition. While Toyota is investing in new four-cylinder engines, Mazda has chosen to return to rotary engines (Wankel), while Subaru has opted for a boxer engine with horizontally opposed cylinders. Investing in new combustion engines does not mean it will be just an evolution of something already on the market. On the contrary, the new generation engines are revolutionary, each in its own way. Moreover, all will be hybridized. Toyota has always believed in multiple solutions, without putting all its eggs in the electric vehicle basket. The cautious strategy seems to have been the most accurate. According to the brand’s data, approximately 70% of vehicles with combustion engines will still be in use by 2030. The electrification of the new engines is not the only way to increase carbon neutrality: the use of various more sustainable fuels also plays a role. “The evolution of combustion engines is constant, and historically, some innovations are crucial to achieving greater energy efficiency, reducing pollutant emission levels, and increasing performance simultaneously. These improvements result from the use of electronic systems and computational engine management systems, including artificial intelligence,” explains Cleber Willian Gomes, a professor of Mechanical Engineering at FEI (Inaciana Educational Foundation). Gomes adds other technologies to the list, such as direct fuel injection, variable valve timing system, turbocharger, and materials that use nanotechnology to reduce engine weight and friction between components, as well as providing greater wear resistance. Let’s start with Toyota, as it is the only one set up in Brazil. Subaru is represented by the Caoa Group, which may mean the new technology will be imported. On the other hand, Mazda left the national market in 1999. There are two new Toyota engines: a 1.5 (available as aspirated or turbo) and a 2.0. The current Toyota 1.5 three-cylinder has not yet been adopted in the country but is expected to come in the new Yaris Cross. With a thermal efficiency of 40%, it is more economical and stronger than the same liter four-cylinder. It’s not the highest index, Nissan vehicles equipped with the e-POWER hybrid system have 50% in this regard. Why develop a completely new generation of combustion engines? According to the brand, the plan was made because the emission laws expected for Europe – whose Euro 7 program will come into effect in 2028 – and the United States would imply reducing power/torque and adopting very expensive catalytic converters. Just as the oil crisis impacted U.S. vehicles in the 1970s and 1980s, when emissions also tightened, drastically affecting engine performance. It seems that the downsizing movement has been reversed here since the new set is four-cylinder. Surprisingly, this is good because the new arrangement allows the cylinders to be lower since they are smaller. This makes the engine volume 10% smaller, making it easier to install hybrid systems. Toyota estimates that a sedan equipped with the new engine will have 12% lower fuel consumption. In addition to being more powerful. Another advantage of these new Toyota engines is the possibility of lowering the hood. The wedge shape is still one of the best ways to ensure a lower aerodynamic penetration coefficient, reducing fuel consumption and emissions. The 1.5 turbo will replace the current 2.5 aspirated from the brand, which is intended for vehicles carrying more weight. Like the aspirated version, the four-cylinder solved the dilemma of the larger engine. If it had to be adapted to the new rules, the 2.3 would have its power cut by 30%. In direct comparison, the turbocharged engine reduces the volume by 20% and is also 15% lower. The 2.0 turbo, on the other hand, will replace the 2.4 turbo, offering 30% more performance and 10% less volume. Like their counterparts, they will also be associated with hybrid systems. “The new engines will run on both regular fossil fuels [gasoline and diesel] and carbon-neutral fuels, including liquid hydrogen, synthetic fuels, and biofuels,” Toyota announces. Regarding the arrival of the new engines in Brazil, nothing is confirmed as they have just been presented. However, the company is globalized, so they are likely to equip Brazilian vehicles in the not-so-distant future, especially due to the federal government’s Mover program, which encourages the production of more efficient and less polluting vehicles. Perhaps we can expect news after 2026 in new generations of the Corolla and Corolla Cross? Subaru Subaru has always been famous for its horizontally opposed cylinder engines, known as boxer engines, also used in old air-cooled Volkswagens and current Porsche models. Unlike an inline cylinder engine, this mechanical arrangement is horizontal, allowing the assembly to be closer to the ground. A lower center of gravity is always welcome. Boxers are not exactly known for their low fuel consumption or contained emissions. But they are so characteristic of the manufacturer. To maintain tradition and, at the same time, increase efficiency, the brand created the new boxer engine generation. “If you just want to increase efficiency, engines with horizontally opposed cylinders are not necessarily the best option. But what would Subaru be without them? If you think about it, we are the only mass-produced brand that is investing in horizontally opposed engines,” says Tetsuo Fujinuki, executive director and chief technology officer of the brand. He states that the goal is to improve “our weakness in efficiency.” Called e-boxer, the new four-cylinder resolved the issue by marrying a hybrid system with two twin motors. There are three operating cycles. The most traditional is when both work in parallel to move the car, perhaps the one with the highest performance. The series parallel combines the most efficient way of managing between the combustion engine, the generator, the battery, and the electric motor, balancing the situation. The third prioritizes electric driving, with the four-cylinder transferring energy to recharge the batteries, leaving the traction to the electric motor. The boxer is not the only characteristic of Subaru; all-wheel drive is also part of the legacy. It will not be different in the new powertrain, where the combustion engine will be primarily responsible for traction on the front axle, while the rear will be driven by the electric motor. But it doesn’t seem to be an arrangement that has become common in some plug-in hybrids, models in which the rear axle is powered only by electricity, without a driveshaft like the Japanese model. The advantage is that the rear axle will always be in operation. All in a compact package. As the boxer is thinner, Subaru managed to install the force control unit in the engine compartment. Normally, it is installed near the tank, reducing the fuel volume. Thus, it will be possible to have a much larger fuel tank, ensuring extensive autonomy. Production will start at the new Kitamoto factory in Japan, and production is expected to begin around September. Mazda When it comes to eccentricity, Mazda takes the prize. Used by the manufacturer since 1961, the Wankel engine (named after its inventor) has three key pieces: a rotor, its box, and an eccentric shaft. The rotor operates in four strokes: intake, compression, combustion, and exhaust. It may seem complicated, but compared to a traditional four-stroke engine, it is simpler since it eliminates components like valves and their control. Mazda has made many generations of this engine, from sports cars to conventional vehicles, all of which have benefited from the compact mechanical package and lower weight. You may be wondering: why didn’t it succeed as it should have? Consumption was high, and, to make matters worse, emissions were also high. “Mazda’s rotary engine is our only internal combustion engine. However, its structural characteristics have repeatedly put us in difficult positions regarding environmental regulations. In the past, it even disappeared from the market. But now, we feel it’s time to turn its uniqueness into an advantage,” says director and chief technology officer Ichiro Hirose. The rotor is so small that it is below the top of the tires, so its center of gravity is very low, not much different from Subaru’s boxer. “This allows a silhouette that surpasses the standards of current combustion cars,” Hirose emphasizes. The fact that all three aim to have lower engines is no coincidence. In addition to lowering the height, they also allow better mechanical arrangement, as well as opening up space in the cabin. The exoticism does not stop there. The new rotary engine is omnivorous, meaning it consumes various other fuels, going well beyond the principle of flex. It can run on ethanol, biofuels (including one made from algae), vegetable diesel, synthetic fuel, methane, and hydrogen. “Due to the need to meet the global market for the sale of vehicles with these technologies mentioned, there is a demand to develop engine versions that can use different types of fuel and even mixtures of them, and thus expand the concept of flex engines beyond gasoline combined with ethanol,” Cleber projects. The manufacturer is still working to improve the efficiency of the project to meet new emission programs, but believes that hybridization will be the redemption of the Wankel engine.
