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Toyota has not ruled out combining diesel power with its proven hybrid technology – beyond its 48-volt 'V-Active' models – but it says petrol is a better choice for electric assistance.
Toyota has left the door open to combining diesel power with its fuel-saving hybrid technology for future examples of the LandCruiser and Prado, but it says such technology may not make sense to engineer and certify under tight emissions rules.
Chief engineer for Toyota's new LandCruiser Prado 250 Series, Keita Moritsu, told Australian media at the 4WD's local launch that stringent emissions standards mean there is more incentive to create a petrol rather than diesel hybrid.
“Worldwide, diesel is of course a very important engine for LandCruiser," said Moritsu-san.
“But with the worldwide [emissions and efficiency regulations], the gasoline or petrol engine is the better technology.
“Especially for the American and Chinese markets, our priority is for the [development of] the gasoline engine at the moment. And that is why we applied the hybrid system to the petrol gasoline engine.”
However, Moritsu left the door ajar for such future technology, depending on changes in regulations across various global markets:
“But in the future, and of course with the CAFE [emissions regulations] situation, worldwide it is changing. So I need to monitor which engine is suitable for the hybrid system.”
Toyota Australia engineer Russel Tomlinson said the characteristics of a diesel engine are such that a hybrid version may not be worth the engineering challenge that would come with developing it.
“The theory is possible, but to respect the challenge, the engineering challenge, to make it practical," he said.
“Because on a diesel engine, you’ve [already] got low-end torque. Which is where an electric motor would feed into a [petrol] engine.
“With petrol, it compliments the whole package. With diesel, you’ve got low-end torque. [Hybrid assistance] might come in mid-stream and get that through the drivetrain, but the difference [in fuel use and CO2] versus the engineering and the effort to put it in, is our challenge.”
Toyota currently offers the Prado's 2.8-litre turbocharged diesel engine with 48-volt 'mild-hybrid' technology, which includes a belt-driven motor/generator that can both harvest energy under braking and coasting, as well as assist the engine with a small amount of motivation.
This technology is available in the new LandCruiser Prado across the range, along with some specifications of the HiLux ute.
Unlike its extensive range of petrol hybrid vehicles – including the Tundra full-size pick-up – Toyota has elected to refer to this 48-volt diesel technology as ‘V-Active’.
This is done to differentiate it from petrol hybrids, which can run on electric power alone – and quote greater fuel savings – thanks to larger batteries, better energy regeneration, and more powerful electric motors.
In other markets, the Toyota LandCruiser Prado 250 Series is available with a 2.4-litre turbocharged petrol hybrid powertrain. Toyota is yet to implement a diesel hybrid powertrain in any vehicle.
Sam Purcell has been writing about cars, four-wheel driving and camping since 2013, and obsessed with anything that goes brum-brum longer than he can remember. Sam joined the team at CarAdvice/Drive as the off-road Editor in 2018, after cutting his teeth at Unsealed 4X4 and Pat Callinan’s 4X4 Adventures.
