Off-roading is a complicated thing, but it’s also quite simple. Yes, there are things like advanced traction control systems and complex dampers and fancy air intakes that affect off-road performance, but the main decider in how good a vehicle is off-road is something you can assess with just a simple glance. Which is why I’m confident when I tell you: The Tesla Cybertruck isn’t going to be “the best off-road vehicle.” But it will probably be a good off-road truck. Here’s what I mean.
The Cybertruck has the makings of a great off-road pickup truck, but it does not have the makings of the GOAT off-roader, no matter how much Tesla fans want it to be. And to be clear: The Cybertruck doesn’t have to outperform the Jeep Wrangler on the Rubicon to be an awesome truck. I think it’s going to end up being a lot of fun, and having seen one just yesterday on the roads of LA, I actually think it looks great.
But I’m here to bring some expectations back down to reality.
“Elon Explains Why the Cybertruck Is the Best Off-Road Vehicle” is the title of the YouTube video above showing Elon talking with Joe Rogan about independent suspension’s advantages over solid axles.
Listening to that, and seeing Rogan’s reaction reminded me a lot of the iPhone crowd explaining technology that Android users have had for years. “The new iPhone 8 is literally the best smartphone ever. It has wireless charging and optical image stabilization — it’s revolutionary!” you’d hear iPhone-ers say in late 2017, five years after the Nokia Lumia 920 Windows Phone debuted with both features and two years after the Samsung Galaxy S6 came out with both, as well.
It’s the same thing here; Musk is describing the most basic concept ever, here — the Cybertruck doesn’t have a diff that hangs down low because it has…wait for it…independent suspension. And oh, the ground clearance changes too?! How does it do that? Well, it has…wait for it…air suspension! Revolutionary!
I’m mostly just poking fun, because the truth is that iPhone users don’t know much about Android phones because they don’t care, and many Tesla owners don’t know much about off-road vehicles because they don’t care. And it’s fine; I applaud both Apple and Tesla for having created a customer-base that’s so devoted and focused. But let’s be real: Independent suspension with air springs is some seriously, seriously basic stuff. I mean, damn, look at this 2011 Jeep Grand Cherokee crush some off-road trails with air suspension:
Again, that’s 2011! A thirteen year-old car!
And here’s me off-roading a 2017 Land Rover Discovery with air springs and independent suspension:
View this post on Instagram
Behold the modern Land Rover Defender, which features independent suspension and air springs!:
And that reminds me, the real start of this whole air springs+independent suspension off-road movement was the debut of the 2002 Range Rover:
More importantly, we need to recognize that every electric off-road vehicle will have this same setup. For packaging, drivetrain efficiency, and unsprung-weight reasons, the solid axle — considered by many the ultimate off-road suspension for its toughness and articulation — is almost certainly going to die with the internal combustion engine. This means all vehicles will go to independent suspension. All of these off-roaders will also have to go to air suspension as well, because the ground clearance required for off-roading comes with far too big of a hit to overall vehicle drag (and thus range) — air suspension is the only way to have good clearance while off-roading and low drag on the street.
Three Things That Could Hold Back The Cybertruck. #1: Articulation
Anyway, now that we’ve established that the Cybertruck’s suspension setup is far from revolutionary (unless they have a trick up their sleeve that I’m not seeing), I can tell you a bit about why the truck is not going to be the very best off-road vehicle out there.
For one, while independent suspension does offer some ground clearance advantages over a solid axle, solid axle vehicles just drive over the tallest obstacles in their way; this lifts the diff on that axle high up off the ground, away from vulnerabilities. If you do hit your diff on something while rock-crawling, it’s not likely to break as Musk says in the clip, unless you’re driving very fast for such rocky off-road conditions. So the ground clearance advantage is real, but it’s not necessarily a humongous benefit off-road given typical off-road driving etiquette.
But the biggest drawback of an independent suspension setup is articulation. Look at the Rivian R1T pickup in the screenshot above; the vehicle is crawling over tough terrain, but because that suspension has so little travel — and because of the way independent suspension works re: roll center — one or more tires often lift off the ground. This not only means you have one less tire to propel the vehicle forward, but also that the ride becomes rather tippy, with the front end shooting into the air and then crashing down. What’s more, this puts lots more pressure on the traction control system to perform well so that torque gets sent to the wheels with grip. Let’s talk about that now.
Three Things That Could Hold Back The Cybertruck. #2: Traction
Go ahead and watch the Rivian R1T attempt to drive through a little V-notch in the mountainous terrain, and see how the nose finds itself jacked up in the air due to the vehicle’s lack of flex. With one fewer wheel on the ground to transfer torque to the road, the Rivian’s traction control system has to kick in, and as you can see in the clip above: It fails epically. The driver finds himself with his foot mashed hard on the accelerator pedal, and the truck just doesn’t move.
While I didn’t experience anything quite that egregious while off-roading the Rivian R1T, I did notice that the traction control system was reactionary, and made the vehicle feel a bit more flinchy and less relaxed as it tried to climb through difficult terrain.
Why? You might ask. Shouldn’t electric drivetrains be the ultimate in off-road propulsion given that they can vary output almost instantaneously (unlike an ICE)? It’s not that simple, as I wrote in my review of the Rivian R1T’s four-motor system:
To climb [a certain] grade at a given velocity (we’ll call it 2 MPH), [a] vehicle requires a certain amount of torque at the wheels. Imagine you’re driving a Jeep Wrangler Rubicon up this grade, and your foot is pressing the accelerator pedal a given amount, causing you to cruise up the grade at a constant velocity.
Now let’s say the passenger’s-side front wheel hits an ice patch and loses all grip, but the driver maintains the same pedal position. Will the tire slip (i.e. will its tangential speed exceed the vehicle speed)? The answer is: only if the three other tires — with which the tractionless tire is mechanically linked — cannot make up for the lost traction.
In other words, if the three tires with grip have enough traction such that the torque at the three wheels equals the required total wheel torque to ascend the grade, the vehicle will keep moving at a steady rate, and the tractionless tire’s tangential velocity at the tread will likely equal close to the vehicle’s velocity. The ascent will be smooth.
Put more simply, let’s just model the Jeep Wrangler Rubicon’s driveline as one big axle with four tires on it. Torque is being sent through that big axle, and all four tires are spinning at the same rate because they share a common shaft. If one or two or three tires roll over ice, the giant axle will continue moving steadily so long as the friction coefficient between the ground and the tire(s) with grip is capable of producing enough torque against the tire to meet or exceed the wheel torque needed to ascend the grade. (Note: There will be a yaw moment depending upon which tires have grip).
I go on:
With Rivian’s system, what happens? Well, let’s again say you’re climbing that same hill with the pedal depressed a certain amount. A given amount of current is being sent to the wheels, producing the requisite wheel torque to ascend the grade at 2 MPH.
Now let’s say the passenger’s side tire loses all grip; what happens? Well, the wheel torque there goes to zero, and the wheel slips until the vehicle can pull current from that motor [and clamp the brake]; does the wheel torque at the other three wheels instantly increase like it does with a fully-locked ICE in order to maintain a steady vehicle speed? Not instantly. The vehicle’s electronics have to quickly send more current to the other motors with grip to keep the vehicle moving at a given rate.
How much current do you send each wheel? What if you send too much current to a wheel that doesn’t have quite enough grip, causing wheel-spin? As for the wheel without grip; should it keep spinning at a rate that corresponds with vehicle speed so that it doesn’t have to accelerate once it does get grip? If so, how do you know what the vehicle speed is?
It’s really complicated.
The rest of that article includes a discussion with Rivian’s Principle Engineer of the drive system, Mason Verbridge. And he admits it’s really challenging trying to figure out what the vehicle reference speed is. How do you find how fast the ground is moving under the vehicle? If only one wheel is slipping, that’s easy enough, but if multiple are, then what? The traction control system has to predict the friction coefficient of the ground and the vehicle speed, and the reality is that often times the wheels will “flare up” a bit before the system can slow them down. This isn’t ideal for off-roading.
The analogies and comments I made about the R1T’s traction control system mostly apply to a four-motor system; I think the Cybertruck is expected to have two or three. Still, I mention all of this because of a recent Cybertruck off-road video, which was the impetus for this article.
The truck tries climbing some grades and struggles for traction in a situation where, clearly, a fully locked drivetrain like one you’d find in a Wrangler Rubicon would fare much better:
Three Things That Could Hold Back The Cybertruck. #3: Geometry
I mention in the lede of this article that off-road capability is something you can assess with just a quick glance at a vehicle, and that’s…somewhat true. Obviously, there are certain elements that have to exist for the vehicle to be good off-road — four-wheel drive, decent gearing, good tires, an OK traction control system etc. — but the most important element of a great off-road vehicle is favorable geometry: That means a compact overall size, low weight, and small overhangs. This is where the Cybertruck is going to be compromised, but not for any reason other than that: It’s a pickup truck. Pickup trucks just aren’t elite off-road vehicles.
There’s a reason that, throughout history, the very best off-road machines have been SUVs: the World War II Jeep, the Toyota FJ, the Land Rover Defender. They all combine solid axles with great geometry, which it’s hard to offer when you have a pickup bed that has to be at least five feet long. You’re either going to have to have that length in the wheelbase or in the rear overhang, and neither does you favors off road.
That’s the thing about off-road capability, especially rock crawling: Unlike racing, fancy electronic tricks aren’t going to save you. Off-roading is a simple game: get good torque to all the wheels, lock them together, and keep the overall dimensions and overhangs small — that’s how you win. There’s a reason why a Nissan GT-R can out-handle and out-accelerate any car from the 1940s, but when it comes to off-roading, one could make the argument that the World War II Jeep remains — even after almost 80 years — the best off-road platform of them all.
I say “platform” because the WWII Jeep could use a locker or two, but slap those in and it is in some ways more capable than any off-road vehicle available today. Just look at the video above! It has short overhangs, a small belly, good ground clearance that can be raised without making the vehicle too tippy or too tall due to the lack of a roof — it’s ideal, even today.
All that is to say: Off-roading requires one to adhere to certain fundamentals, and the Cybertruck, by virtue of being a modern electric truck, cannot. It’s going to be big because it’s a pickup truck. It’s going to be heavy because it’s electric and has to meet modern crash standards. Its articulation is likely going to be limited because it needs independent suspension for packaging space and driveline efficiency. Its traction control system isn’t necessarily going to be as good as a fully mechanically-locked system for the reasons I mentioned above (the video seems to imply that Tesla is still working on it).
I’m not saying the Cybertruck isn’t going to be great off-road. The Rivian R1T (which also features independent suspension, air springs that jack ride height way into the stratosphere, torquey electric motors, etc.) has fantastic approach, departure, and breakover angles for a pickup truck, which is why I consider it among the most capable of all trucks currently on the market.
I don’t know if the Cybertruck in TFL Off-Road’s video is at max ride height or is outfitted with the biggest tire package, but I can tell you that the wheelbase looks humongous, and that rear overhang doesn’t look ideal, either:
There’s no way to get around that. This falls into the “fundamentals” category. Yes, you can jack up the ride height via air suspension, but that’ll only go so far before CV angles become a problem. Even if you can jack up the ride height, think about how tall the vehicle now becomes. Getting it through tight trails might then become even more of a challenge.
Again, I’m not saying the Cybertruck won’t be great off-road, and overall I’m quite excited for its release. I believe it will be quite good, but all the Tesla fans who think it’s going to be the best off-roader out there, just look at the screenshot above and then look at this, and you’ll see that it doesn’t even pass the “glance” test: