Toyota uses combustion engines in a similar way to some automakers that make big promises about EVs that won't be released for several years. The new four-cylinder internal combustion engines (ICEs) were presented as work-in-progress advancements at the end of May, far in advance of their deployment in production automobiles. The Chief Technology Officer of the Japanese manufacturer is now giving further information regarding future developments.

Hiroki Nakajima described the new 1.5- and 2.0-liter engines as, in an interview with Automotive News, a possibly "game-changer solution." He said they will be "completely different" from the present generation of ICEs. Even if sales of hydrogen-powered vehicles haven't exactly taken off, Toyota claims that its engineers' work on the slow-moving Mirai has improved their understanding of engine heat efficiency.

Although Nakajima could not provide numbers, Toyota achieved 40 percent some years ago. Nissan claims an even higher 50 percent because of their e-Power technology, which uses the combustion engine to feed a battery rather than power the wheels. Similar measures have been adopted by Mazda, another Japanese carmaker, using the rotary engine inside the MX-30.

The new engines would have shorter piston strokes, which Toyota's CTO noted was "a very difficult task" to achieve. All of these inline-fours will be downsized in order to "revolutionize vehicle packaging," which will allow lower front ends to have higher efficiency through improved airflow. An electric motor's quick reaction will make up for any torque lost throughout the operation. The main focus of development for these new engines is hybridization.

It is anticipated that the first vehicles equipped with the new engines would go on sale in 2027. Toyota is creating powertrains that can run on hydrogen, biofuel, and even synthetic fuel in addition to fossil fuels. This new engine family "has lots of room to play," according to Nakajima, implying that there are a lot of engineering gimmicks the business isn't yet willing to share.