Tesla Semi Walkaround & Discussion at ACT Expo w/ Dan Priestley

Added: 2026-05-12

[00:00:07]Hi everyone. We're uh back at the ACT Expo. We're actually in the parking lot here. I'm with Dan Priestley, the director of engineering for the Tesla semi-truck. So, we're super excited to talk about some of the things and, you know, Dan's going to help us step through some of the things that maybe we saw in the public space, but we want to confirm directly and then just talk about some of the attributes that make a Tesla semi-truck a Tesla semi-truck and talk through some of those differences.

[00:00:31]So, Dan, thanks for taking the time and uh and stepping through some of those things with us.

[00:00:35]>> Yeah, happy to chat.

[00:00:36]>> Appreciate it. So, Dan, I know, you know, one of the things that we' started talking about offline was the aerodynamics. is probably one of the more, you know, stark or obvious things that you see when you look at the truck.

[00:00:46]You know, if you don't, if you've never worked in the CFD space, you look at it and you might wonder why it looks that way. Maybe it's just a design, but maybe talk a little bit about the the cab design, the focus on arrow, and the importance of those things to an application like this.

[00:01:02]>> Yeah, the aerodynamics are key because it's about 50% of the energy that you use just to move the truck down the road. You have to overcome that aerodynamic drag. And so by making the truck as aerodynamic as possible to do the same amount of work, have the same amount of range, it means you need less battery to do the job. Less battery is less cost, it's less mass, and less mass begets mass. So you get even less mass for supporting said battery. And so you really end up in a situation where aerodynamic improvements have this massive compounding effect on the overall efficiency and that's total cost of ownership of the truck. And achieving that requires looking at it from the ground up from day one. Taking a lot of the lessons that we've had over from the passenger car side, whether that's smooth underbody a treatment, really studying how air flows around the wheels and tires, spending a lot of time in the wind tunnel, but then also challenging some of the ways that traditional trucks have been designed. One things that unique on that front is that uh this is a hard-mounted cab to the frame structure. So the fully integrated chassis and the the cab actually work really well together. This is not an independently suspended cab. And what that really does is enables maximum aerodynamics because you aren't worried about this compliance between a moving cab and the fixed panels that are on the chassis. You can remove those as potential sources of drag and optimize your aerodynamics again in the chase of lowest total cost of ownership.

[00:02:22]>> No, it makes perfect sense. And I mean some of those things are subtle cues, but if you talk about them all of a sudden, you know, if you've seen trucks driving around the road over the road trucks, you would see that a lot of these gaps that are maybe belt line or slightly below. If you look at, you know, some of the other name plates in this space, they're large gaps and they've got sort of this treacherous looking path near those. And that's to make up for those dynamic envelopes and the movements relative from the cab to the frame.

[00:02:49]>> That's right. So at I mean at what point when when you guys were endeavoring to design this you know from the arrow perspective was that a known thing sort of at the beginning of development it's like you know what one of the best ways to get rid of that gap is to go hard mounted cab or was that along the development process you're like you know these gaps are just not great how do we get rid of that and so you you sort of you know iterated your way into the omission of that isolation. Well, there was another factor here and that is that in a traditional truck where you have that forward engine and that long drive line that runs along the the whole body length of the truck and then you get to the rear axle where you have to make this sharp 90° turn for torque delivery to get out to the rear wheels. Well, when you do that, you're invoking a very serious moment on the total frame of the vehicle. And if you watch traditional trucks with that longitudinal drive line, even if it's electric, you end up twisting this whole chassis. And that's not something we wanted to do. One is those transitions in torque delivery are inefficient. So again, back to you need more battery than to do the same job. So we're chasing efficiency, but also is that because we like to integrate the battery structure right in with the rest of the vehicle structure. We don't want that whole vehicle twisting. We want to treat this much more, you could say, like a unibody, >> like a unibody, >> right? So it's much more car-like in that respect. So the battery structure and the chassis of the vehicle, the frame rails and everything associated with supporting the rest of the vehicle work together in harmony. So you don't have these independent entities. So when you can really lock down the integrated chassis, what we call the skateboard with the drivetrain, the battery, the front subframe, and all of those other bits, and you integrate that all together, you can then hard mount because it's not twisting and shaking the same way that a traditional truck is because you don't have that compliance.

[00:04:29]>> Totally makes perfect sense. And I think one of the things you said earlier was you were talking about the cascading or knock-on effects of weight begets weight and costs cost and those things. I think about the battery pack as one of the biggest functions of that, right? The the mass reduction coupled with the aero improvements that we're making, those can relate directly to kilowatt hours that need to be carried by the the truck. Now, it's a unique scenario on a truck where the the total mass of the truck when pulling a trailer, you may actually want to provision for that. So like as you were sizing the battery pack for the specific application, was there like a realized savings that you got from the aero efforts and from the mass efforts or did you have to size the battery packs to what is really the total load which includes the trailer?

[00:05:15]>> Yeah. So, it's a balance of those factors and we do actually internally have a >> how much a kilogram is worth and how much a count of drag is worth and if we can pull that out of the truck, how does that compound into the value because of payload a customer could potentially haul. So, it's a way to help levelize everything.

[00:05:33]>> But when it comes to the practical implementation of the truck, it's a balance where you need enough energy to do the job. You need enough energy on board to drive the range to slot directly into a diesel operation from a time perspective. Y >> but at the same time if you have too much battery then you've displaced payload and you've knocked yourself out from being compatible with a number of those operations. So it's about finding both of those. What's that sweet spot and I think that we've really landed you really close to that optimum in the two different variants of the truck. Here we have the long range truck. So 500 miles on a single charge. You're really starting to see where you're exhausting drivers hours of service. You coupled with fast charge, you can slip seat this thing. So you can slot in operationally with no dedicated charge time. You're doing it while the driver is taking a break. So no time explicitly for charging. Y >> and then simultaneously the longrange truck can haul a 45,000lb payload with a typical drive van. So you've got both time par as well as payload par. And that's really the key. And then for those that are really mass sensitive, standard range is a great option. For those just those don't need that much energy, standard range is a great option. So it's about finding that balance again, maximizing the efficiency, minimizing TCO, but ultimately you we're trying to make the best truck and that means it's got to fit into all of the operations that we can both from a time perspective as well as an energy and uh miles perspective.

[00:06:54]>> That totally makes sense. You know, I I would I would want to get to the back and talk about some of the battery integration and and what we're seeing on the chassis of the vehicle, but maybe as we walk back there, I'd want to understand, you know, as we look at the other competitors in the space that have tried to launch electric semi-truckss or are talking about it or have done, you know, maybe it's not a full-blown semi-truck, but they're heavy duty applications. A lot of them have not been successful in those endeavors. And and I attribute that to a couple things.

[00:07:22]You know, one, it's a it's a tough industry. It's a tough space period. But two, they a lot of those companies that tried to do that and didn't do well didn't have I'll say the the tenure in industry and all the experience that a company like Tesla has, you know, I mean, how much of an advantage from your view was it taking all those things from, you know, the S, the X, the model, you know, the Model Y, the the all these battery pack integrations, all these structural integrations, you know, was that a huge contributor or did you have to rethink a lot of that because the application is so different?

[00:07:56]I'd say it's a bit of a mix, but for the most part, you are absolutely right that we've benefited hugely from the experience and success that the light duty side of the business has had.

[00:08:05]Absolutely. And that comes from whether it's a design ethos of challenging all of the specifications like the best part is no part integrating those structures really challenging that uh you know from day one on the truck design you know but it's also even today leveraging componentry. So you know the drive inverter and stator are shared from Cybertruck. Y >> the uh you know HVAC compressor is actually shared with CyberCap. So the upcoming product uh there's light modules are shared from other vehicles as well. We tried to pull in I mean the screens you just start picking apart these parts and those are key enablers both for reliability and cost. So it really enables us to have a successful product because those are two very important things in the semi-truck space. That's not to say that we haven't thought about things a little differently.

[00:08:53]>> And you know, structurally, there are problems to solve on the truck that you don't have to solve on the car side.

[00:08:59]>> Sure.

[00:09:00]>> For example, I mean, we are still about only a quarter of the combination weight. Your vehicle dynamics are largely dominated by the trailer, which we don't have, but that you're carrying.

[00:09:10]>> Yep.

[00:09:10]>> And so, how does that play into the structures of the vehicle? How does that play into the vehicle dynamics? That's a lot of learning that was new and bespoke for semi but you know we still understood at the end of the day how to make an effective electric vehicle in that from all the learnings that we had on the light duty side. Yeah, there is this I would imagine there's a strange function in this particular application where this lowest common denominator of having this huge trailer with this payload is driving a lot of the structures that we're seeing where you know in the passenger car even if it's got a towing capacity like a cybert truck or or something like that. You know the I think the phrase comes to mind in this case it's literally like the tail wagging the dog to a degree you know with a mass of of that capacity. So um that makes sense. Dan, you know, look at looking at the back, is there is there anything that you would want to talk about on the architecture side that you know you think is particularly um impactful or unique here? And then maybe beyond that, we could talk a bit about total cost of ownership.

[00:10:06]>> Yeah, I mean I think right away you'll notice that we have that e- axle. So again, we're not doing this longitudinal drive line. We have directly mounted motors on the drive axle and we have uh two different styles. The first the four axle or the mid axle really is our torque axle. So it's got uh two motors that are independently driven one to each wheel and that is designed for high power events. So those are the takeoffs, those are your high-grade overtake applications and then the rear axle is the efficiency axle.

[00:10:37]>> These two axles are geared differently but then underneath share a lot of the same components. So they share oil pumps, they share rotor stator and inverter all the same in every position.

[00:10:48]So that's where that scale really helps.

[00:10:51]So we're not bespoke making uh those expensive components if you're trying to do them individually. We are trying to commonize across platform as well as within the vehicle itself. So, uh, you know, the twin axle setup here really gives an operator all the benefits of a 6x4 in terms of maximum traction, torque, and power to do the job while also then all of the efficiency of a 6x2. Because at highway speed, when you're on, you know, cruise and you're, you know, not encountering large hills, that torque axle disconnects, wheels still spin, but there's no windage losses. There's nothing internally spinning. And so, that's what unlocks a really great highway efficiency.

[00:11:29]>> Totally. It it makes me think of, you know, I think some of the Tesla models and and other OEMs as well have deployed, you know, for like a rear traction motor, it'd be a PM machine and then the front they'd be an induction machine so that there weren't coging losses if you wanted to go up to cruising speed. But when you need the torque and when you need the power delivery, you can trigger that. So, similar concept, slightly different application in this instance.

[00:11:51]>> Yep.

[00:11:51]>> Makes perfect sense. Dan, from the, you know, total cost of ownership piece of this. This is this is something that, you know, it's it's such a unique application. It's a bold move taking an electric vehicle into a space that has obviously been for the past 100 years dominated by the, you know, the diesel truck application. How how is Tesla looking at considering messaging the total cost of ownership benefit? And and I mean maybe down to like a driver if if a driver was sitting with us or maybe it's a fleet owner operator type of person like how how are we expressing the total cost of ownership advantage to something like this versus the next diesel partner down the road?

[00:12:31]>> Yeah. I mean I think there's a few things uh to touch on that point. I mean one is on the TCO piece. Yeah. That's the underlying success for everybody because if you're have a successful business, you've got a lower total cost of ownership. That means that you're going to be able to provide freight for cheaper. So truck carrier wins, driver wins, those that you're hauling freight for win. That's the best scenario. And so you really that has again become our ethos is chasing total cost of ownership. Now like how that applies different parties like we still have to solve for all of them. We sometimes say that the the three customers that matter are the driver, the fleet owner, and then the shipper who's providing the goods. And you have to make something that works for all three. If you make something that doesn't, it's not going to be an acceptable product. And so, you know, with that, even though we aim for total cost, that doesn't mean that we're trying to make a bad experience. On the driver's side, we've made it very comfortable. We've brought over, you know, an in-house seat architecture I think is going to uh drivers are really going to love. And then on the fleet manager side, we've brought over the reliability, you know, the things that, you know, make Tesla uh and EVs great.

[00:13:34]We brought over that reliability, something they can count on day in day out. And then from a shipper perspective, again, it's just the like lowest total cost energy throughput that lowers their shipping cost. So overall, we've really tried to tackle that on multiple fronts and ensure each one of those key partners in the space is taken care of.

[00:13:50]>> Yeah, makes makes perfect sense from from a charging infrastructure perspective, you know, both on the vehicle side as well as, you know, the hard infrastructure side of it, you know, this is Tesla's quickest charging product that's in the marketplace today, you know. So megawatt, you know, plus charging units, right, that Tesla is now, you know, engineering and and and launching and doing all of those things.

[00:14:15]You know, what what is the you know, are there any concerns right now with launching a product like this and having those chargers stood up in time and like this this this sort of ven diagram of all these these attributes and you know the the three personas or customers that you articulated and getting the infrastructure in place in time like how how is that from your view sort of shaping up recently?

[00:14:38]>> I mean the charging is progressing really well. We've got about 50 different sites that are in some stage of work. I mean, some of them are still in design and phasing, but we are like actively working on a bunch with some actually opening here within the next month or two. And so, we're going to be in a position that as trucks you really start to roll off the line, they will have charging available because we recognize right now it doesn't matter if it's public or it's private.

[00:15:02]>> Whatever truck that we build, charging has to already be in existence in that location. Yep. So we have to really match charging with every truck that we deliver. And so we're laser focused on right now making sure that those customers are going to have something that works for them on day one. So a charging solution needs to be identified. And you know we've been working really closely and leveraging all of that experience that we have on the light duty side. I mean at this point the supercharger team has deployed more than 80,000 DC fast charging posts worldwide and they work closely with all the utilities and so they understand the process to go and deploy the charging that we need at the scale, at the speed, and work closely with utilities, all of our customer partners, and anybody else in order to get that on time so that the truck can hit the ground running day one.

[00:15:48]>> It makes a lot of sense. I think you have to cater to the partners, you know, your prospective customers for something like this, you know, but that tailored approach of saying, "Here's a truck, here's the infrastructure that goes with it." And we're tailoring how we build out that infrastructure relative to, you know, the markets of destination and where these vehicles are going and making sure that we're not selling trucks in in areas where we can't go and do the charging. That's encouraging to hear.

[00:16:10]>> Yeah. And also on the charging point is that now we've announced you know people can go and buy on you know online our uh charging cabinet both for the fast charging so the V4 with 1.2 megawatt capability or what we call the base charger the 125 kowatt charger because depending on your operation one might work better than the other and so this is a great chance for whether it's folks deploying charging at their own site or other parties that want to get into the charging game itself. It provides a unique opportunity uh you know for folks now to get that full spec sheet priced right up front, see it online and you know run with it on their own.

[00:16:44]>> That's fantastic. Well Dan, I know uh we we talked with the team offline. We want to get out to the site. We want to walk through the manufacturing facility, maybe dive into some more of the architecture, which you know I know for the folks on the Monroe Live uh channel, they'd love to dive into. I personally want to dive into it. We we appreciate you taking the time and we're excited about what you guys are doing.

[00:17:03]>> Well, this is great. Happy to chat.

[00:17:04]We're really excited. Uh, and yeah, we'd love to have you out and have a chance to do a tech deep dive at some point because there's a lot of amazing engineering work that went into this.

[00:17:11]And you know, it's not going to stop.

[00:17:12]We've got plenty of improvements planned to come down the pipe, but uh, overall uh, Tesla's done a great job and I'm super excited to get this into high volume.

[00:17:20]>> Totally. Awesome. Thanks, Dan.

[00:17:21]Appreciate the time.

[00:17:22]>> Thanks so much. Take care. Thank you.

[00:17:23]Thanks, everyone.