Hirochi eSBR 500X (with actual gearbox! ) 1.0

Alternative mod name: the Porsche Taycan we have at home
BACKGROUND & LORE
It is commonly known that electric motors, due to various factors, have decent torque and therefore power output at lower RPM but suffer greatly from the diminishing of torque and power at higher RPM. In fact, this is why most EVs have staggering acceleration but dismal top speed.

Spoiler: Torque curve of the IRL Motive MV255 electric motor

At first the torque curve remains high and flat. However, as the RPM increases the torque begins to fall dramatically. This diagram doesn't show the actual power, but in practice, the power in the end would be dropping quite a lot. Source: https://dergipark.org.tr/tr/download/article-file/616285

The issue of optimal performance being limited to a specific RPM range isn't new, however. In fact, all ICEs, as far as I am concerned, also face the exact same issue. However, in their case, the problem is typically that high performance comes only at high RPM.

Spoiler: Torque and power curve of the IRL 2018 Ford Focus RS

As you can see, at lower RPM ranges the torque and power output is quite miserable. Source: https://www.automobile-catalog.com/curve/2018/2453705/ford_focus_rs_hatch.html#gsc.tab=0

Since this issue isn't new at all, how did we deal with this problem before with ICEs? Well, the answer is simple: we added gearboxes to the transmission.

Spoiler: Simulation done by YouTube channel @d4a

The engine used here is a low torque output engine that revs very high so that it has massive power at higher RPM but miserable power and torque at low RPM. The engine directly drives the wheels. As we can see, at the beginning the engine had a hard time driving the wheels. The car finishes quarter mile in 11.092 seconds.

After introducing a 4-speed manual transmission, the results got improved to 9.711 seconds which is quite a bump from the previous 11.092 seconds. This definitely shows how crucial transmission is to ICE vehicles.
Source:

As we all know, gearboxes did serve us well in the past. However, it seems that every EV on the market simply uses direct drive transmission. Why is this happening? Well first, direct drive is more simple and more rugged than a gearbox; second, we actually have an exception: the Porsche Taycan.

Spoiler: Photo of Porsche Taycan

(yup, that Taycan the design elements of which gets copied by basically every recent sport-ish Chinese EV)

The Taycan features a two-speed transmission to, at least theoretically, have both good low-speed acceleration and high top speed. This is because the use of a multi-speed gearbox enables the car to maximize the utilization of the high-power part of the torque curve, just like how gearboxes on ICE cars work.

Spoiler: The ZF 2-speed gearbox used on the Taycan

Now! Let's get back to our BeamNG lore universe. The Gods of the BeamNG world (aka the awesome devs) gave the world engines with accurate torque curves as if they are IRL engines.

Spoiler: Torque curves of engines in game

↑Torque and power curve of the Hirochi Sunburst 2.0 Sport RS AWD

↑Torque and power curve of the Hirochi eSBR 300

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Therefore, Hirochi, improving their eSBR and trying to market it as a sport EV, faced the same problem that Porsche faced IRL. Apparently, Hirochi internally split into two factions on the issue of diminishing performance at high RPM: the "muh power gang" and the "big brain nerds". The former faction came up with the power behemoth eSBR 800 with over 800ps, while the latter faction came up with what this mod is all about: the eSBR 500X.

While both the eSBR 500 and 800 uses individual electric motors for their front and rear wheels, for the sake of cost-saving and using existing tooling (and actually also for the limitations of the game engine), the eSBR uses a single 500ps electric motor taken from the eSBR 800 to power all four wheels through the AWD transmission system built for the ICE SBR4s. This allows it to share many transmission parts with the regular SBR4s, therefore reducing the cost and simplifying aftermarket modifications since now you can just get the ubiquitous SBR4 differentials, transfercases, gearboxes, and so on, and simply slap it onto the eSBR 500X. The 2-speed gearbox is simply a scaled-down version of the 7-speed DCT used on the SBR4s for maximum production line reusing. It's also a very good gearbox to work with.
Despite having slightly less peak power than the regular eSBR 500 (512ps vs 528ps), in actual testing, the eSBR 500X actually does 0-100kph slightly faster consistently.

left: 0-100 with eSBR 500; right: 0-100 with eSBR 500X
At the same time, it also has a much higher top speed of a whopping 337km/h, thanks to the maximized utilization of its peak power made possible by the 2-speed transmission.
Sadly, the car did not sell very well. Most ordinary people don't care about performance at all, and all they care is the price of the vehicle. eSBR 500X, being slightly more expensive (primarily due to that high performance motor which costs 29500 BeamBucks instead of 7000+7000 for the front+rear motor combo on the regular eSBR 500) and offering no exceeding advantages, is therefore not really appealing. For motorsport enthusiasts, they soon found that the transmission tends to break after being abused with the immense low-end torque and acceleration. Though Hirochi soon remedied the issue by strengthening the parts, the car still only appealed to a very small niche of people, and its sales were negligible compared with the sales of the more orthodox eSBRs.
Development Notes
During the development of the engine, the biggest problem I faced was the fact that I have to make the engine's vehicle controller ICE to actually make it compatible with transmission parts. (Don't worry, it makes proper EV sounds and has no exhaust. ) The issue I run into is, when I set the "friction" to the same value as the performance electric motor on the original eSBR, the engine just refuses to start. I also ran into the same issue when I made my constant power engine block mod. That time, I solved the problem by leaving friction as it is, and manually adjusted the torque at different RPM to make the power output constant. But this time, I have to make the torque curve matching. The thing is, in the official documentation, nothing is mentioned about engines.
So I desperately asked around, and one dude (@Happyhusky) suggested that I should take a look at the old, unmaintained wiki page.
And boy did it help.

So apparently by default the starterTorque is determined by the engine friction. Therefore, when the friction is too low, the engine refuses to start. However, by manually assigning a value, we can successfully solve this issue.
Since this is not mentioned in the official documentation, I can see this as being potentially intriguing and irritating for a lot of other modders, so I'm here to tell everyone about it!
KNOWN ISSUES & CAVEATS
It is previously mentioned that this engine still uses ICE vehicle controllers. In fact, it is still identified as a gasoline engine and runs on gas, so it's equipped with a fuel tank instead of a battery pack. It also needs to be manually started if the engine is stalled or shut, although it basically starts instantly and its idle is ridiculously low (50rpm).
The engine still uses the visual flexbody of the 2.5L flat 4, to use the JBeam mesh of the existing engine to ensure that it works with all the transmission parts.
If you notice any bugs or have any suggestions, feel free to tell me in the discussion thread or the Discord post!
Future Plans

• more motor & transmission options
• more configurations
• just adding more stuff to the mod ig

And finally some...
Self promotion: if you are interested, consider checking out my config pack mod: Actually-Being-Comfy Drivability Enhancement Project (Project: Alphabet). It's also a very high quality mod, featuring hundreds of finely-tuned configs!