Great Wall tore Huawei apart like an assassin who wanted to kill the extended range

To mitigate this disadvantage, extended-range hybrids such as Ideal generally use large batteries (PHEV), using a larger "reservoir" to try to meet the high power requirements when cruising at high speeds. The cost is naturally higher battery costs; performance is limited when the battery is too low to be replenished; if users rely entirely on fuel and do not connect to charging piles, the user experience will be compromised.

Therefore, for consumers who often commute long distances at high speeds, especially those who often commute at high speeds and find charging inconvenient, extended-range hybrids such as Ideal and Wenjie are not the best choice. Although there are not many such consumers, they are not so few that they can be described as "very few".

On the other hand, the reasons for abandoning direct drive capability are related to the actual needs of most users and the development choices of car companies. First of all, although there are a considerable number of consumers who clearly know that they have more high-speed needs, the car needs of most consumers today are actually daily commuting in congested urban environments, but the degree of concentration varies.

The lower the speed, the less congestion, the less value there is in direct drive. Drivers know that stop-and-go traffic consumes the most fuel, and even a series-parallel DHT will tend to use the series-extended range mode. For most consumers who only occasionally drive on the highway, the lack of direct drive in the extended range mode is not unacceptable, and the high energy consumption of high-speed cruising will be averaged out by a large number of daily commutes.

Although the mechanical structure required for direct drive is not heavy (especially compared to large batteries), the added complexity cannot be ignored, especially for multi-gear series-parallel DHTs, and the daily maintenance rhythm is basically the same as that of pure fuel vehicles. In theory, extended-range hybrids without direct drive are more likely to achieve better mechanical reliability and maintainability.

Geely Hi·X DHT Pro, dual planetary gear structure

The more decisive factor is actually the company’s own development path.

Internal combustion engine direct drive is not high-tech, but there is a threshold for new car manufacturers who have no relevant experience. This threshold is not a crude "can't make or can't adjust", but under the general trend of electrification, new car manufacturers will not be willing to invest in mechanical transmissions that are time-consuming and labor-intensive, but may not be used for a few years, even if they have unlimited resources.

This is true for the accumulation of technical experience, and even more so for the production supply chain and after-sales system. If a new car manufacturer chooses to use direct-drive DHT, even if it has transformed into pure electric vehicles ten years later, it still needs to provide mechanical transmission support for today's small batch of hybrid vehicles. This decision is obviously not necessary. Traditional car companies that already have a large number of fuel vehicles to "serve" do not have this concern.

The development needs of vehicle platforms also make new car manufacturers prefer extended-range hybrids that are easy to derive pure electric versions. For example, Wenjie can even launch a rear-wheel drive single-motor version like electric cars; while DHT hybrids with direct drive must be front-wheel drive-based because of the mechanical transmission structure. This is nothing for traditional independent car companies with "foundations", but it is an extra layer of cocoon for new car manufacturers starting from scratch, so it is unnecessary.

NV's extended-range, pure electric dual-power

In the face of reality, theory should be put aside

This is actually a very typical "simple system vs. complex system" problem.

Does a simpler system with some structures removed necessarily mean worse performance? If the answer is yes, how do we explain that among all the DHT hybrid technologies of domestic brands, the BYD DM-i, which is the simplest, is in short supply? If market results do not necessarily correspond to product effects, is i-MMD/DM-i the worst DHT? I'm afraid not.

No matter how sophisticated the structural principle is, the final effect is determined and influenced by each subsystem and each component. No matter how perfect the principle is, it depends on the material process to become a reality. The principle of gas-operated automatic rifle is more advanced than that of bolt-action semi-automatic rifle. However, if you use soft plastic 3D printing to print an AK-47, you dare not compete with the original 98K in the middle door.

Applying the limit method, if a series-parallel DHT has a direct drive compared to a range-extended hybrid, but the vehicle weight is 1 ton more, does this direct drive capability still have any meaning? If the thermal efficiency of the internal combustion engine of the DHT is 10% lower than that of the range extender of a range-extended hybrid, can the direct drive help the DHT hybrid recover from the disadvantage? Such examples are too easy to cite.

Of course, in reality, everyone is more of the same, no one has black technology, and no one is too bad. Then the final product result depends on the superposition of the advantages and disadvantages of each subsystem and subcomponent. The lack of direct drive in the extended-range hybrid is entirely possible to be compensated by more efficient range extenders and motors; the series-parallel DHT has more working mode options, but if the transmission system efficiency is too low, it is enough to drag down the entire system.

Great Wall Lemon DHT two-speed transmission

Even if the parts are well made, software and tuning still affect the finished product. Simple systems may provide fewer combinations, which theoretically limits the maximum performance of the system, but there are fewer and easier to find available paths. The extended-range model only provides electric drive, so only electric drive needs to be considered, while DHT needs to consider various possible combinations of direct drive and electric drive.

Complex systems offer more possibilities. In theory, they can achieve greater performance after precise differentiation, just like some multi-gear DHTs provide double-digit working modes. However, on the one hand, the patience and time required for tuning work increase dramatically. On the other hand, even if the theoretically optimal operating map is found, the actual execution of the parts may not be as smooth as in the simulation software, so those execution actions that have little effect need to be eliminated.

All of these require time, resources, and increased risk. This is a dilemma of how to strike a balance, and there is no absolutely correct direction; at the same time, you need to be aware of your own relevant capabilities, and the best choices for different manufacturers should be different.

Whether you eat the advertisement or not, you know the effect

Even if the technology achieves performance advantages, there is still a problem that one cannot do anything about: Are these advantages easily perceived and felt in actual use by users? Let’s take an extreme example: suppose a user has a traffic jam effect, and is always stuck when going out, and the speed never exceeds 40km/h. Even if the DHT with the lowest speed of direct drive intervention is used, it will not be much better than the extended range type.

In reality, in the DHT hybrid world with different levels of complexity, DHT technology with more gears and more complexity often corresponds to a higher HEV model tendency. This is consistent with the fact that extended-range vehicles without direct drive gears are now mostly developing into ultra-large battery PHEVs.

Geely Hi·X and Lynk & Co EM-F with three gears, both brands launch HEV models for the first time

Many people know that the efficiency of electric motors can be as high as over 90%, far exceeding the thermal efficiency of the most efficient internal combustion engines of just over 40%. However, similar to internal combustion engines, the efficiency of electric motors will also decrease under certain operating conditions such as low speed and high load, and can sometimes be lower than 80%.

Therefore, for HEV or non-plug-in PHEV, since the battery power is completely obtained by the internal combustion engine burning oil, if there is no direct drive, the energy utilization efficiency of the fuel under extremely low-speed conditions may be as low as 40% (internal combustion engine thermal efficiency) × 90% (oil-to-electricity conversion loss) × 80% (low-speed motor efficiency) ≈ 29%.

Of course, this is just a random estimate, but the approximate order of magnitude is enough to illustrate the problem: after a round of oil-to-electricity conversion in the series mode, the utilization rate of fuel energy can be very low, sometimes even so low that "it is necessary to consider whether direct fuel drive would be more economical."

Therefore, manufacturers such as Great Wall, Geely, and Chery, which need DHT to take into account the HEV market, have increased the direct drive gear of DHT to expand the speed range of engine intervention. By using a richer combination of oil-electric driving force and flexibly adjusting the load ratio of the fuel engine and the motor, the lowest possible comprehensive energy consumption performance can be achieved.

BYD DM-i does not consider HEV at all. For PEHV connected to the power grid for charging, since electricity is much cheaper than fuel, energy utilization is no longer an indicator that needs to be calculated. Car owners will panic when looking at the numbers on the fuel gauge, but they will not care so much about the extra few yuan in electricity bills. As for PHEV users who are not convenient to charge, they have their own expectations that fuel consumption will be higher than charging, which is a tactical abandonment.