Toyota’s next-generation hybrid combustion engines draw hydrogen lessons from the Toyota Mirai for 2027

Toyota has already confirmed it will invest more than €13 billion in the digitalisation and electrification of its range. Even so, combustion engines paired with hybrid technology (as shown in the featured image) will remain a cornerstone of the line-up-and, above all, of the Japanese brand’s finances, after it recently reported record profits and record sales for the 2023 financial year (Japan’s fiscal year ends in March).

Speaking to Automotive News, Hiroki Nakajima, Chief Technology Officer at Toyota Motor Corporation, reiterated just how important these powertrains still are, while sharing further information about the company’s next-generation engines.

The promises are bold. Nakajima says the technology is entirely different and "can change the rules of the game". In his words, it is a "super engine" not in terms of power, but in terms of efficiency.

Hybrid combustion engines remain central to Toyota

According to Nakajima, Toyota is developing a new engine family that, while still based on internal combustion, is intended to deliver a step-change in efficiency-especially when integrated with hybrid systems.

Hydrogen teaches Toyota new tricks

In comments to Automotive News, Nakajima provided a few specifics about these engines. For the first time, he referenced displacement-specifically 1.5 and 2.0 litres.

Two very conventional sizes which, he says, will feature "potentially revolutionary solutions" and be "totally different from today’s combustion engines".

So where does the revolution come from? From what Toyota has learned through the Toyota Mirai. By studying the thermal behaviour of hydrogen in the fuel cell stack, Toyota’s engineers have been able to transfer some of that knowledge back to the "old" internal combustion engine.

What will change?

As a reminder, Toyota’s current hybrid engines claim energy efficiency of around 40%. So when the brand talks about "changing the rules of the game", it likely points to another leap in efficiency, achieved through more effective combustion processes.

Details remain limited, but the direction is becoming clearer. Nakajima noted that the new engines will use a significantly shorter piston stroke. This should support higher power at higher engine speeds, but it will reduce low-rev torque delivery. To make up for this loss of pulling power at lower revs, Nakajima emphasised the importance of combining the engines with hybrid systems.

Ignition control and hybrid pairing

Toyota’s biggest progress is therefore expected mainly in these areas: managing the engine’s ignition timing and optimising how the combustion unit is matched with the electric motor. Nakajima says this new engine family will provide "a lot of freedom to play", implying there are further engineering solutions the company has not yet revealed.

Earliest launch date: 2027

As for timing, these new Toyota combustion engines are still some way off. Nakajima points to 2027 as the earliest date for this next generation of engines to appear in the brand’s models.

Source: Automotive News