Creating a Positive Future for Combustion Engine Cars: Mazda’s Public Proof-of-Concept Testing for Carbon Neutral Combustion Engine Car

You've probably heard the term "carbon neutral": balancing CO₂ emissions with absorption to reach net zero. But Mazda is pushing further to pursue carbon negative, where absorption exceeds emissions. In other words, the more you drive, the more CO₂ you reduce.

All engines release CO₂ when they run, whether they burn fossil fuels or biofuels.*³ But biofuels are made using processed plant oil, and as plants absorb CO₂ when they grow, the CO₂ released when driving is the same CO₂ the plants absorbed—making biofuels appear to be carbon neutral. 

However, processing plant oil into usable biofuel takes energy, and this in turn emits CO₂. Still, while not being completely carbon neutral, biofuels can reduce CO₂ emissions by up to 90% compared to fossil fuels.

Yet Mazda wanted to take it even further. Even if the negative impact is small, it can still prevent you from fully enjoying the driving experience. But what if driving could do something positive for the environment? That would ease the concern around environmental impact and let drivers embrace the road with a clearer conscience.

This was the thinking behind Mazda’s carbon capture device.

With this technology, the CO₂ absorbed during biofuel production normally emitted when driving is instead captured by the device.

In the future, CO₂ absorption is expected to exceed emissions, leading to a reduction in CO₂  the more you drive.

EVs often dominate the conversation around environmentally-friendly vehicles. But Mazda sees a role for combustion engine cars too, from both a practical and emotional perspective.

Yuji Harada, Research Manager for CO₂ Capture Technology at Mazda, explains.

Yuji Harada wants to create products that are good for people and the planet   . When he shared this conviction with colleagues, he persuaded two others to launch the CO₂ capture research team with him.

There are practical reasons to consider gasoline cars in tackling environmental concerns. Right now, the electricity powering EVs still often comes from fossil fuels like coal and gas. That will change over time as renewable energy expands.

But that won’t happen everywhere. In regions with limited infrastructure, or countries that can’t afford to switch to renewables, there will still be demand for efficient, high-performing combustion engine cars. And as a manufacturer, we have a responsibility to address environmental concerns in those markets too. Creating combustion engine cars that consider their environmental impact isn’t optional. It’s part of our duty.

Yasunori Uesugi oversees race operations and technology testing. A calm and composed leader, his many years of experiencing engine development have made him an engineer at heart.

Mazda also produces EVs, and we fully appreciate what they offer. But we don't think EVs should be the only choice.

Many drivers love what makes combustion engine cars special. We don't want environmental concerns to take that choice away from them. We want a future where people can still choose the car they love, where all kinds of vehicles share the road. That's the spirit driving this project.

Mazda has outlined three steps for its CO₂ capture technology.

Step 1, CO₂ adsorption, is where Mazda #55 comes in.

Takahiko Yoshida, Factory Motorsports Promotion Department. He leads the technical demonstration of the CO₂ capture device on Mazda #55. Drawing on his experience reducing CO₂ in production processes, he's now taking on the challenge of CO₂ capture in race vehicles.

Even reaching the first step, CO₂ adsorption, meant overcoming more challenges than we imagined just to install the technology in a car and race it. We built the system from scratch, and issues only emerged once we started running at the circuit. It came down to the wire. But engineers, designers, and specialists from across the company came together to get us here. Now that we've completed the Super Taikyu race, we want to build on this important first step.

Ryota Tottori, Engine Design Engineering Department. He designed the exhaust components for Mazda #55, working to ensure the CO₂ capture device functioned properly while maintaining performance as a racing car.

The CO₂ capture device on Mazda #55 is still quite simple. The capture volume is low enough that air cooling was sufficient. But to reach the next step, we need to increase that volume. That means more complex systems: water cooling, mechanisms to remove moisture that interferes with capture, and a way for customers to easily remove the captured CO₂.

The hard work is just getting started.

By completing the Super Taikyu race, Mazda proved that carbon negative is more than a dream. But this is just the beginning. 

The challenge of creating a combustion engine car that can be positive for drivers and the planet has only just started.