More Logical Than Ludicrous: Tesla Semi Will Need to Deliver Reliability

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As dramatic as the surprise unveiling of a second-generation Tesla Roadster was last week, the world does not need yet another electric supercar. What it does need is an alternative for the two-thirds of freight activity that is carried out by pollution- and carbon-dioxide–belching diesel trucks. Which is why the Tesla Semi is potentially far more important.

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According to the International Energy Authority, trucks burn about half of the diesel consumed worldwide every year and have accounted for about 80 percent of the increase in diesel demand since 2000. If that trend continues, diesel trucks alone will be responsible for nearly 10 percent of all energy-related carbon-dioxide emissions by 2050.

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If Elon Musk has his way, the Tesla Semi will change all that. Not only will the world’s first battery-electric Class 8 truck have a range of up to 500 miles, it will benefit from a network of solar-powered Megachargers that allow it to run (eventually) on pure sunlight.

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But as so often with Tesla products, many questions remain. Musk shared only selected technical and commercial details about the Semi, and Tesla continues to face severe financial, logistical, and manufacturing challenges as it struggles to bring its Model 3 to market. As impressive as the Semi prototype’s launch was last week, the cutthroat world of commercial trucking will need hard facts and harder numbers before fully embracing Musk’s ray of sunshine.

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Musk introduced the Semi as he does most Tesla vehicles: touting its performance. While this is arguably the least important aspect of a commercial vehicle, Tesla has a brand image to maintain, and so the Semi can accelerate briskly from zero to 60 mph in five seconds without a trailer or in 20 seconds with a full load. It can also maintain a higher speed up a grade than existing diesel trucks.

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At the launch, Musk told owner-operators, “If you’re pulling a load up [the] Rockies, you’ll earn 50 percent more per mile than in a diesel truck.” But this is hardly representative of most routes, and it applies only to drivers who are paid for their time rather than the distance they travel.

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Range Life

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Semi-truck range is far more crucial, and there were cheers when Musk announced that the Semi with a full load will be able to travel 500 miles between charges (there will be a 300-mile version available). “With 80 percent of routes under 250 miles, you can go to your destination and back even if it has no charging,” he said.

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This statement, too, bears investigation. According to the American Transportation Research Institute (ATRI), which carries out a detailed survey of trucking companies every year, only 21 percent of trips made in 2016 were less than 100 miles (thus, a 200-mile round trip). A further 40 percent were between 100 and 500 miles. That means the longer-range Tesla Semi should be able to manage about 60 percent of one-way journeys, but possibly far fewer round trips, without recharging.

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Tesla would not reveal the lithium-ion battery pack’s exact capacity or chemistry, but an engineer did say that it is very similar to one of the company’s energy products, probably either the Powerwall domestic or Powerpack utility-scale battery.

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If a trucker does have to recharge, Musk promised, the process will be painless at a new generation of roadside charging stations called Megachargers. Although no specifications were given, these will be more powerful than Tesla’s existing 480V/120-kW Superchargers and will deliver 400 miles of range in just 30 minutes. This dovetails neatly with legal break requirements for commercial drivers in the United States, Musk noted.

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However, the existing network of more than 1000 Superchargers in Asia, North America, Europe, and the Middle East has taken years to build out, and upgrading those will take time. No details were given on how long it would take a Semi to recharge at an existing Supercharger—or even if it would be able to do so.

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Reliability Really Matters

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Musk also touched on another concern of commercial fleet operators: reliability. Fixing a broken-down electric truck could be beyond the abilities of many smaller or rural truck mechanics across the country for some time. Musk got another cheer when he said Tesla will guarantee that the Semi will not break down for a million miles. That is a reassuring number for truckers because it is significantly farther than the average of 750,000 miles that operators told ATRI they cover before selling a truck.

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That reliability comes from having no transmission or brakes to wear out, although the Semi does use air disc brakes as a safety measure to complement its regenerative braking. It is also thanks to the Semi’s unique drivetrain, which uses four individual Model 3 motors, one on each of the truck’s four drive wheels. A failure of one or even two motors would not prevent the Semi from continuing to outperform a diesel truck, Musk said.

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Nevertheless, Tesla said that large fleet customers that typically carry out their own maintenance will be given the tools and access required to service the Semi themselves. Tesla also expects to depend heavily on its mobile service technicians and perhaps even embed them with key customers.

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Although the Semi comes with an Autopilot system almost identical to that found in Tesla’s cars (with a few additional radars), the emphasis is on safety rather than automation. All Semis will come with automated emergency braking, lane-keeping assist, and forward-collision warning as standard, as well as a new technology to detect and prevent jackknifing by independently controlling each of the four drive-wheel motors and brakes.

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In the cab, a centrally positioned seat should simplify production for the global market, and twin screens identical to those in the Model 3 present the essential readings plus navigation, fleet management software, and driving settings. Whether the touchscreen displays might present ergonomic challenges to drivers was hard to judge during a short tour of the vehicle. There is no internal camera to watch the driver as on the Model 3.

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Operating Cost: The True Test

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But for all the Semi’s design flourishes and its potential environmental benefits, the big decision for many truck buyers will come down to dollars and cents. Will the Semi be cheaper to run than a traditional diesel truck?

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Musk said it will. On the same 100-mile route and with the same load, he said, the Semi would cost $1.26 per mile to operate compared to $1.51 for a diesel truck. That figure compares well to the $1.59 per mile calculated by ATRI for operating a diesel truck in 2016. Saving 25 cents per mile would allow the Semi to offset its higher retail price in two years, according to Tesla. ATRI reported that an average truck drives just over 100,000 miles annually. That implies the Semi will cost $50,000 more than a typical $150,000 diesel truck, for a list price of around $200,000 (probably for the 300-mile variant). Neither Musk nor Tesla provided pricing for either version of the Semi.

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However, the situation is more complex. Musk did not break down the cost per mile into its various components, including such unknowns as insurance, maintenance, and driver wages. More important, the $1.26 figure is based on charging the Semi at a Tesla Megacharger, where Musk promised that truckers would be able to buy electricity at just seven cents per kilowatt-hour (in the United States, at least). Although Musk has long promised that Tesla’s charging network will ultimately be powered by Tesla-made photovoltaic panels, it is still in the process of building its first Supercharger station with an onsite solar array, and the company has not released data on its use of renewable power.

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Charging at seven cents per kilowatt-hour would be a bargain compared to the national average rate of 13.1 cents. But if truckers have to recharge using a local utility in the absence of a convenient Megacharger, their energy savings would shrink considerably. Tesla claimed that the Semi uses less than 2 kWh per mile of operation. Recharging the Semi from public supplies in California, for instance, where electricity costs 19 cents per kWh, would add 24 cents per mile and almost wipe out its cost advantage. In Connecticut, Alaska, and Hawaii, where electricity is priced at more than 20 cents per kWh, the Semi would lose money.

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Musk claimed that platooning three Semis into an Autopilot-controlled convoy would slash costs further, to just 85 cents per mile—at which point he says it would even be cheaper than rail freight. However, aerodynamic research prepared for the Federal Highway Administration found a potential maximum fuel saving from platooning of just 7 percent, corresponding to $1.17 per mile for a Tesla convoy.

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• Electric Big Rig: Cummins Shows Battery-Powered Semi before Tesla
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• New Tesla Roadster: Zero to 60 in 1.9 Seconds, 250-MPH Top Speed, 620-Mile Range
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• Tesla Model 3: Everything We Know
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No doubt many of these questions will be answered as Tesla moves from the two working prototypes it showed last week to full production of the Semi by 2019. Tesla said it already has “lots” of reservations for the Semi, including from Walmart and trucking giant J.B. Hunt Transport. Whether they turn into sales that can make a significant dent in the 250,000 diesel trucks bought each year remains to be seen.

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