Will your cybertruck rust?
TL;DR probably…
Teslas Cybertruck is without a doubt polarizing. An unreasonable car for unreasonable people. But at least it tries to innovate — albeit with mixed success. In my opinion there are two aspects of the car that stand out. The use of stainless and steer by wire. Let’s look at both
Stainless steel is problematic
Why stainless steel? It is of course a tough material that is essential in industrial use. But it is not the totally impervious easy-care magic metal Tesla wants to make us believe. In fact many applications use stainless because it allows for thorough cleaning and not because it does not have to be cleaned.
But let’s dig a little deeper:
Tesla describes it’s steel as 30x like. This means that the metal contains at least 16% chromium plus nickel. The 300 series contains hundreds of alloys like 304 which is something your cutlery most likely consists of, or 316L which contains an additional 2.5% molybdenum and is much more corrosion resistant.
Tesla patented several alloys which might be used for the cybertruck. If we look at their corrosion resistance, and especially at the pitting resistance number we can see, that these alloys lie between the aforementioned 304 and 316L alloys.
In simple terms: stainless does not rust, because the chromium part of the alloy aggegates at the surface, building a protective layer. But the layer can be removed. Especially chlorides can carry away chromium, slowly depleting the protection. And salt is everywhere.
Here is a nice summary for seawater resistance. The insidious part is, that you don’t need to drive to the coast to be exposed to sea salt. Wind transports miniscule amounts miles into the mainland. The same goes for deicing salt. Stuck in a crevice in humid environment and even 316L steel will start to rust. The only solution is constant cleaning.
Another source of chlorides are gastric acids. Depending on the diet, bird poop can be pretty aggresive. And let’s not talk about vomit. This will not dissolve the metal, but create nasty discolorations.
And chlorides are not the only problem. Flash rust can stick to the car body. Long term exposure to acid rain (still a thing) and nitric oxides in the atmosphere will darken the metal.
One problem the car might not have is galvanic corrosion. Only very few metals are more electronegative than stainless, and most people don’t transport their gold and silver reserves out in the open.
What does that mean? In simple terms: Depending on your environment and cleaning habits, your truck will rust. Only on the surface, but still: your car will show it’s age. Put your cybertruck in a dry garage, wash it on a regular basis and it will last for decades. But so does every other modern car. Which begs the question: Why? In the long term, cars are consumables. Even if the chassis is kept in perfect shape: Battery, motors and electronics will degrade. This was no problem for a deLorean, as the perishable parts were standard components, but an EV is different. Nobody will be able to produce a replacement mainboard for a Tesla in a decades time. Battery technology will advance and get incompatible. Stainless won’t prolong the life of your car in a meaningful way.
Steer by wire?
If you have ever watched a Youtube video about the cybertruck, there is the moment where someone says: “Oh by the way, it has steer by wire” Only to change the subject immediately. For good reasons. Imagine driving your car, and the hydraulics pump fails. In this case there is still a mechanical connection that makes steering harder, but possible. Depending on the situation, you are in grave danger, but you are theoretically still in control.
In the case of steer by wire: The wire is cut and you are toast. You literally loose the control over your vehicle. Steer by wire or steer by hydraulics has technically been possible for decades and are very safe as multiple redundancies have been built in. Even EU regulations allow for it. Getting rid of the steering column removes a major safety hazard. But all car manufacturers refrained from it for a very simple reason: The idea of loosing control over your vehicle is absolutely horrifying. This is a very rare event. But a single event of this kind would let the sales figures plummet to near zero. And once hundreds of thousands of cars drive on the road, this kind of fringe event is inevitable.
But this is Tesla. No words about multiple redundancies or emergency protocols. They are not even trying to emphasize the safety of the system. And given Tesals track record for handling problems with their cars, I would not feel safe in a cybertruck.
A dead end
The cybertruck is a technological island. There cannot be a smaller version due to the weight. It has no overlap with the Semi. The production line can’t be retrofitted to other models due to the choice of stainless steel. Tesla wasted time, money and resources that were needed for a smaller Model 2 car.
