Is the design of the Tesla Semi evolving?

Spy shots of Tesla Semi Truck prototypes have started popping up all over the country. The Tesla Semis spied in different states seem to be the same truck, but looking closely, we can spot a few differences. So what's different? And how do these differ from earlier prototypes?

Above: Silver Tesla Semi Truck prototype at the 2018 TSLA shareholder meeting (Source: S.P. Walker / Twitter via X Auto. Posted with express permission)

First, Tesla has made a few slight changes to the exterior of the class-8 electric hauler that suggest the automaker is performing further R&D. By testing these trucks on public roads, Tesla has been gathering real-world data for a few years now.

I decided to compare a few of the recently spied Tesla Semis from behind — where they have different electrical boxes installed in back. This, potentially, indicates that Tesla is also experimenting with variable electrical and battery management systems.

Above: Diagram: Latest changes that Tesla has made to the Tesla Semi Truck’s exterior. (Sourced: Illustrated by Iqtidar Ali / image by Cory Draper (full video below). Click/Tap to open  in new tab)

A look at the side profile of the new Tesla Semi Truck prototype seen via the video of the Trucker/YouTuber Cory Draper reveals a few things.

Above: A sneak peek at the new, evolving design of the Tesla Semi Truck (YouTube: Cory Draper)

Tesla has made several small and big changes to the side profile that I've tried to illustrate in this diagram (see above). The changes I highlighted in this prototype can be compared to the official photo of the Tesla Semi shown in the file photo.

Exterior Design Updates

Following is a list of five modifications I noticed with the exterior design update of the latest Tesla Semi prototypes:

1. Roof cab length is reduced by about 50% (visual estimate), this area previously expanded to the entire cabin’s length as seen in the official photo (above).
2. Roof cab height is also reduced significantly, but Tesla has been varying it (likely during testing) from the start. This is probably done to obtain an optimum point between utility and aerodynamic drag reduction.
3. Window expansion / Sleeper cabin: The most significant change I encountered in this prototype is the expansion of the ‘window’. Now it expands to around 70% of the rear cabin (area behind driver’s compartment). I think this could showcase a transition converting the area to a sleeper cabin as Tesla has previously hinted was in the works. In one of my 2018 articles on the Tesla Semi spotting, I speculated this area would converted and this space would be used as a sleeper cabin.
4. A black box above the second cabin (sleeper) can be seen in the side profile photo above. This space was previously hollow. Truckers need a sleeper and Tesla is surely going to give them one.
5. The rearmost panel has also extruded out a little and the curve on the bottom has been shortened to adjust for the modified side profile.

Electrical System Variations

The following photos of the rear area of the Tesla Semi Truck show two variations of an electrical systems box. In one prototype, the box looks like a rectangular chest placed in the middle. The other prototype’s electrical system casing is more rectangular and smaller in size, it’s also placed on the left side rather than the middle.

To better convey the differences, I have named these electrical junction box variations, Design Type 1 and 2. This used to be a deep hollow space in prototypes seen before this one (photo below), now they have utilized the space more efficiently.

Above: Tesla Semi Electrical System Box. Design Type 1. (Source: Image: Cory Draper / YouTube. Click / Tap image to open high-res version in new tab)

Above: Tesla Semi Electrical System Box. Design Type 2. (Source: Image: Cory Draper / YouTube. Click / Tap image to open high-res version in new tab)

Above: Space behind the cabin of an early Tesla Semi prototype. (Youtube: Sean Mitchell, full video and article here)

And that's not all. Further differences can also be spotted via a recent Instagram post (as reported in Electrek) — check out the intriguing video and photos demonstrating even more design experimentation below.

View this post on Instagram

A post shared by SacTesla (@sactesla)

Instagram: sactesla via Electrek

So when will we stop seeing these prototypes and finally see the official production version of the Tesla Semi? In a company email last year, Elon Musk told Tesla employees that it’s time to bring the electric Semi to volume production but the timeline appears to have been pushed to later this year.

Fast forward to the recent Q4 2020 Tesla Earnings Call, and Musk claimed that the Tesla Semi Truck would require at least five times more batteries than a car. And, according to Teslarati, in a recent podcast with Joe Rogan, Musk confirmed that the Semi would be equipped with a whopping 500 kWh battery pack. That's a lot of batteries compared to Tesla's sedans and SUVs produced thus far.

Regardless, more and more companies are pre-ordering the electric hauler. Tesla just received its biggest Tesla Semi Truck order towards the end of last year. Interest appears to be growing rapidly for the Tesla Semi, but battery supply will need to ramp quickly to meet this demand. 

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Written by: Iqtidar Ali. An earlier version of this article was originally published on Tesla Oracle.