When the Li Auto ONE was first released, many users criticized its 1.2T three-cylinder engine. Not only does it have three cylinders, but its power is also too low relative to the size of the vehicle, and its efficiency isn't impressive either. In short, it wasn't seen as a good choice.
Initially, many people were skeptical about the engine selection, but as time passed and more people gained driving experience with the Li Auto ONE, the engine seems to be less of an issue now, at least judging by the recent monthly sales that have repeatedly surpassed 10.000 units.
So, how should we view the engine choice for the Li Auto ONE?
Here's the basic structure of the Li Auto ONE's range-extended system, something well-known by all. How should we evaluate this solution?
In four words: "Standard and Conventional."
The range extender (engine), generator, battery, and electric motor are arranged sequentially, each performing its respective function. There are no glaring issues, but no standout features either.
Looking at this setup, you certainly won't feel the same sense of surprise and admiration that you might have when first encountering Toyota's THS (Hybrid System). The design doesn’t evoke a "Wow, what kind of genius came up with this?" moment.
However, we must acknowledge one thing: if transitioning to a fuel cell system, the Li Auto ONE would have the lowest technical conversion cost, bar none. Other systems like THS, iMMD, DMi, DHT, etc., would all require a complete redesign of the powertrain, whereas the Li Auto ONE would only need to replace the components in the blue box with a fuel cell. If the size fits, there might even be a possibility for retrofitting already sold vehicles.
So, what power output would be needed if it were a fuel cell?
This is a question worth considering. The Li Auto ONE is equipped with two electric motors totaling 240 kW, with the main power output relying on the battery. While a fuel cell can directly drive the motor, expecting the fuel cell to be the primary power source is excessive and would be a waste of resources.
The fuel cell's tasks are essentially twofold: first, to directly supply power to the motor when appropriate, and second, to recharge the battery during driving to ensure the vehicle's range.
As mentioned earlier, the battery is the primary power source during high-power conditions, with the fuel cell playing a supplementary role. So, its power requirement mainly revolves around recharging the battery. The Li Auto ONE’s battery pack has a capacity of 40 kWh, which should last for about an hour unless you're pushing speeds of 160-180 km/h on the highway. A 120 kW fuel cell could theoretically fully charge the battery in 20 minutes, which is entirely unnecessary.
The final power output would certainly be a balanced decision. A simple analysis suggests that a more aggressive choice of 40 kW would be sufficient. The Li Auto ONE requires around 30 kW of power to maintain a 120 km/h cruising speed on the highway, so direct drive would not only suffice but also allow for some surplus energy to recharge the battery. With proper SOC (State of Charge) management, it could meet 99.99% of driving scenarios, with only extremely rare conditions of prolonged high power consumption potentially draining the battery. Even in that case, parking for an hour would fully recharge it.
Being more conservative, a 50-60 kW power output would more than suffice, shifting the focus from power size to the cost of different power fuel cells.
The same conclusion applies to the range extender and generator. Thus, the 96 kW 1.2T engine from Dong'an is sufficient in terms of output power. However, the key factor is not the maximum power of the engine but its optimal efficiency power, which is crucial for a range extender.
If we reverse-engineer from the fuel cell requirements, the ideal engine for the Li Auto ONE would be one that doesn’t need excessive power but can operate efficiently at optimal power output, particularly when used for generating electricity.
Clearly, while the 1.2T engine from Dong'an meets the power requirements, it falls short in efficiency.
According to official data from Dong'an, the engine's peak efficiency is 36%, with user tests showing a thermal efficiency of 32-33%. Considering generation losses, we can estimate it at around 30%.
Now, let's compare this to the industry benchmark, BYD’s DMi system, which boasts a thermal efficiency of 43% for its dedicated hybrid engine. Assuming similar generation efficiency, BYD’s actual generation efficiency is estimated at 36%, and likely even higher in reality.
The apparent gap is only about 6%, which doesn't seem huge, but let's calculate it.
Assuming both systems need to generate 10.8 kWh of electricity, the Li Auto ONE would require fuel energy equivalent to 36 kWh, while BYD would need 30 kWh, marking a 20% difference. If we refine BYD’s generation efficiency further, this gap could widen.
What does this mean?
If the Li Auto ONE’s engine and generator could match BYD’s efficiency, its fuel consumption could be reduced by 20%, dropping from the current highway cruising level of 8.x liters to below 7 liters, with a corresponding increase in range.
This improvement doesn’t require advanced combustion theories or complex engine control systems, just a more efficient engine under single operating conditions.
For Li Auto, developing a new range extender engine from scratch may not be realistic. The focus would be on whether they can procure an efficient enough engine from external suppliers. Power isn’t the issue; efficiency is, and this highlights the pain of lacking core technology.
However, given the current technical performance of this Dong'an engine, it’s not unreasonable to expect more.
In conclusion, the biggest shortcoming of Li Auto’s powertrain system is the engine, not in terms of power but efficiency. It’s far from excellent—barely adequate.
It remains to be seen whether Li Auto will continue to rely on Dong'an or find a better alternative.
