The World’s Most Efficient Diesel Engine Is Chinese. It's a Godsend for the Industry But Useless For Your Car

It may sound like a joke, but China—which is leading the world’s transition to electric cars by setting the gold standard for this technology—hosted the 2024 World Congress on Internal Combustion Engines.

The event was held in Tianjin, near Beijing, and featured the unveiling of one product caught the world’s attention. We’re talking about Weichai Power’s diesel engine, which has achieved an efficiency that has never been seen before.

The World’s Most Efficient Diesel Engine

Weichai Power has unveiled a diesel engine that is, quite simply, the most efficient ever. The China Automotive Technology & Research Center, a specialist in testing internal combustion engines, confirmed this milestone, as did the prestigious TÜV SÜD, an international technical provider of testing, certification, inspection, and training for various industrial sectors.

According to Weichai Power, its diesel engine has achieved an efficiency of 53.09%. This record figure is the result of a development born in 2015, with a machine that has been improved year after year to achieve more percentage points of efficiency.

In their latest efforts, the developers of the diesel engine have worked on high-expansion combustion to improve efficiency by 0.3%, mixed-flow turbocharging (+0.25%), and high-efficiency injection (+0.2%). All this, together with a 0.15% improvement in efficiency due to low-friction components, has helped the company increase efficiency from 50.23% in 2020 to 53.09% in 2024.

These seemingly minimal improvements are truly spectacular advances. In terms of fuel economy, going from an efficiency of roughly 46% to 53.09% should reduce diesel consumption by 14%.

Based on these figures, a tractor using this engine and traveling about 155,000 miles per year (250,000 kilometers) would save about 3,170 gallons (12,000 liters) of diesel fuel, or roughly $13,500 in annual savings. However, it's no coincidence that Weichai Power has used the fuel consumption of a tractor as an example for its fuel savings comparison.

Will We See This Engine in Our Cars?

Although it offers greater efficiency, we won’t see this engine on the road, at least not in a passenger car, since it’s an inline six-cylinder that utilizes its 2,336-pound weight to produce 530 horsepower. And even though it doesn’t look like it, it’s tiny.

The only way to achieve this efficiency is to use a huge engine with a very low revolutions per minute (rpm). The maximum torque of this engine is enormous (1,844 foot-pounds force), delivered between 1,000 and 1,400 rpm. To give you an idea, experts don't recommend changing gears in a diesel car until after 1,500 rpm.

A diesel engine for passenger cars has an efficiency of between 30% and 45%. To get better numbers, you need gigantic engines, like those used in large stationary generators or on ships.

As such, “miniaturizing” this diesel engine for use in tractors, with a weight of less than 2,500 pounds, is a milestone. Even if we don’t see it in our cars, it’s useful for trucks and agricultural vehicles, where the transition to electric vehicles is more complicated than in the consumer world.

Image | Weichai Power