Automobile drag coefficient (also known as Cd) relates to how aerodynamic a vehicle is when it’s met with air – this affects efficiency, wherein an electric vehicle this can have an impact on the driving range. Designers working on the next electric vehicle have their work cutout: new EVs have to look good and have excellent aerodynamics so that they can run for a longer time on a single charge.
Initially many, including the WhichEV staff, thought the Tesla Cybertruck would suffer from a lot of drag, whereby it would score a high Cd – a number closer to 0 has the lowest/best drag coefficient. However, new CFD (computational fluid dynamics) analysis from Justin Martin, an aerospace engineer, suggest the Cybertruck is far better than we originally thought.
Following a post on Interesting Engineering, Elon Musk, CEO and co-founder of Tesla, went on Twitter to say: “With extreme effort, Cybertruck might hit a 0.30 drag coefficient, which would be insane for a truck. Requires tweaking many small details.”
Rightfully so, as a 0.30 Cd would put the boxy Tesla in the same category as the Mercedes-Benz CLA 250 a four-door subcompact executive car, and the all-new Toyota Corolla hatchback. You’d expect two small-sized vehicles to be more aerodynamic than the mahoosive Tesla Cybertruck.
Put into perspective, the original Tesla Roadster scored worse with a Cd of 0.35, while the Model X, S and 3 all did better at 0.25, 0.24 and 0.23, respectively.
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Well, no one else did it so I did. Here is the #CyberTruck in CFD. What intrigues me is how well this works. While it may occur to be happenstance that the aero turns out quite well, I believe this was actually the result of very clever design. Ease of manufacturing in flat panels, significant use of triangulated body parts, etc. I won't quote a drag coefficient, as I dont want to put words in anyone's mouth, but I will place money on it being much lower than most sports cars (due to down force), and nearly any (1/2 ton) truck period. Further, I believe the vortex shed over the bed walls helps act to "seal the bed" when the cover is open. I havent modeled the open bed yet, but it sure seems promising. Further, it appears the front end is designed to almost entirely blank out / shield the wheel well…. The cad file is dimensionally correct, all angles and curves are as close as possible. There are some uncertainties such as fenders and wheel well air-exhaust etc. Lastly, at 65mph the local velocity over the roof "peak" is 88mph. Is this the ultimate Elon Easter Egg? @tesla #Tesla #TeslaTruck #CFD @elon
The above CFD isn’t pinpoint accurate, as the vehicle has yet to be released and Martin was purely basing his calculations and modelling on what he could find about the vehicle on the internet. As such, drag could be better or worse, but from his pictures, it would seem the engineer has done a good job in replicating the pickup truck in his software.
It’s important to know that a low drag coefficient isn’t an end-all to a vehicle’s efficiency, as you have to remember to factor in friction from the large tyres and the payload, which we assume will be large, notably as the Cybertruck is designed to transport goods. Some vehicles, such as Formula 1 racecars, even have a bad Cd rating, but that’s because they’re trying to create more downforce so that the vehicle sticks to the ground; Formula E racecars, on the other hand, are a lot more similar to conventional road cars – they’re trying to lower the drag in order to improve the vehicle’s efficiency.
What you should take away from all of this is: the Tesla Cybertruck might be more efficient than any other pickup truck that’s ever been made. Its radical design might look odd, but it looks like there’s a reason behind all of this madness – to create the most efficient pickup truck the world has ever seen. Smart move, Tesla.
It’s paramount that the manufacturer tries to achieve a low Cd as the top-spec Tri Motor AWD model is claimed to have a driving range of over 500+ miles. We suspect one of the driving factors will be the vehicle’s efficiency. Let’s see what Musk and his team can deliver; will they manage to pull it off? We’ll find out in late 2021.