The internal combustion engine isn't going down without a fight. Toyota, Mazda, and Subaru made that abundantly clear when they announced a joint effort to develop new combustion engines in 2024. Rather than sharing the same powertrain, each automaker would pursue its own technology: Toyota would work on a new family of smaller, more efficient four-cylinder engines, Mazda would continue developing its rotary and a new inline-four Skyactiv-Z, and Subaru would stick with its beloved horizontally opposed boxer.
Since then, Toyota and Mazda have offered more details about their respective plans. Subaru, however, has been relatively quiet about what comes next for its signature engine layout. That's finally changing, with the Japanese automaker providing a closer look at its next-generation boxer and revealing an ambitious target: 50 percent thermal efficiency.
