This year China will see its solar capacity outstrip its coal capacity for the first time, according to an industry group.

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Automated Vehicles (AV) are getting a lot of attention at the moment, specifically Waymo’s robotaxis. This stems primarily from a congressional hearing that took place on Wednesday about the future of self-driving cars in America, as well as scrutiny of robotaxi safety after a Waymo robotaxi hit a child in Santa Monica, California. Luckily, the kid was okay, and there’s an NHTSA investigation looking into the incident, which is good. We should be scrutinizing all incidents with AVs, we should be studying how they work in our greater, largely human-driven environment, and we should give real thought not just to how these companies are operating and managing these cars, but how we want them to be operated and managed. What certainly doesn’t help any of this, though, is alarmism, both relating to the role of the human operators and where they’re located.

It was during these hearings that the fact that Waymo robotaxis will sometimes reach out to human “fleet response” operators was first revealed, dramatically, by Waymo’s chief safety officer, Mauricio Peña, probably sweating lavishly as he was grilled by senators like Ed Markey (D-MA). Well, I mean, “revealed” and “dramatically” are only true if you, say, ignore the fact that Waymo has never kept the fact that they use remote human input to assist their robotaxis when needed, as they describe in some detail in this post from May 2024.

Media outlets have been treating this operational fact as some kind of wild gotcha, as you can see in headlines from a Google search:

While some of these headlines describe what the remote operators do as “assist,” which is really a more accurate way to describe what’s happening, some really went for it and cast the situations as people from an island nation outside of America’s direct influence are “controlling” 4,000-pound driving robots in our cities. The website Futurism had what may be the most alarming headline, which they changed about three or four hours after the story went up:

Let’s just be clear about what’s going on here: humans, no matter where they are, are not driving Waymo robotaxis. I spoke with Ethan Teicher at Waymo to confirm all this, and from what I was told – and what is described in Waymo’s 2024 post on the subject – the Waymo Driver (that’s what they call the combination of hardware and software that actually drives the car) – is always in charge of the actual driving of the vehicle, for better or for worse.

From that post:

“In the most ambiguous situations, the Waymo Driver takes the lead, initiating requests through fleet response to optimize the driving path. Fleet response can influence the Waymo Driver’s path, whether indirectly through indicating lane closures, explicitly requesting the AV use a particular lane, or, in the most complex scenarios, explicitly proposing a path for the vehicle to consider. The Waymo Driver evaluates the input from fleet response and independently remains in control of driving.”

No one is driving these cars remotely; in situations where the Waymo is confused, it may call for assistance and get guidance from fleet response. This seems pretty clear when you think about some of the dumb and obvious mistakes Waymo robotaxis have made over the years, like when, this past October, a Waymo robotaxi seemed to be absolutely baffled by one of the most obvious vehicles on the road, a schoolbus. If a human were driving, no matter where they were, they would not have made as many misguided driving decisions as the Waymo Driver did.

And yet, despite the fact that Waymo using remote people to assist the cars was no secret, we still get videos with titles that start with “SHOCKING REVELATION“:

Here’s the thing, though – why is any of this “shocking?” It’s a good thing that these cars reach out to humans to get input about complex or confusing driving situations. Why wouldn’t you want a robotaxi to be able to escalate a situation to get input from someone who understands how the world works? This should be – and probably is – a default expectation for any organization looking to field automated vehicles into public areas.

Now, the part about these remote operators being staged in places like the Philippines may be a bit more complex, but I also feel like there’s a lot of alarmism going on there, too. Let’s be honest: we know fundamentally why Waymo has these centers in the Philippines. It’s cheaper! I mean, come on, that’s not really hard to figure out. It’s not like Waymo was looking for the country with the world’s finest drivers; if that were the case, all these centers would be based in Finland.

And, yes, sure, Waymo is expanding globally and will be launching robotaxi service in Tokyo and London soon, so having multiple locations for their fleet operators makes sense from that perspective, too.

But if you watch that video clip, the Senator is suggesting that these remote operators being outside of America is a security risk, and I think that’s a bit misguided. They’re remote; even if they were located in Kansas, if a malicious entity wanted to hack that line of communication between a fleet operator and the robotaxi, they could do that regardless of where they are. Cybersecurity issues aren’t constrained by geography.

Now, the point about jobs being shipped overseas, I think, is more valid; it used to be that local taxi service jobs simply couldn’t be outsourced to another country, and now they sort of can be. That’s not great! AI takes away enough jobs as it is, so perhaps some restrictions on robotaxi companies moving all the jobs to countries where they can pay people less should be imposed. But that’s not the same thing as the implication that non-US-based fleet operators are a huge security risk.

If you’re worried about humans influencing Waymos to do bad things, it should be reassuring that the Waymo Driver system is always in full control. As Waymo’s statement notes:

It is very important to note, however, their role is never to drive the vehicle remotely. Our technology, the Waymo Driver, is in control of the dynamic driving task, even when it is receiving guidance from remote assistance. Fleet response agents can provide additional context requested by the Waymo Driver (often in the form of multiple choice questions). The Waymo Driver can then appropriately accept or reject Fleet Response agents’ suggestions.

Now, if your concerns are with the decisions that Waymo Driver makes, maybe this is bad news. But if you’re worried about someone getting a job at a Philippine-based Waymo fleet operations center to try and guide a Waymo to, say, drive into the big creepy clown on the Circus Liquor sign in North Hollywood, I don’t really think that’s a valid concern.

There are still plenty of big, important issues yet to be solved with AVs, whether they’re robotaxis or automated delivery vehicles or whatever. We’re only at the very beginning of this journey, and it’ll go a lot easier if we can keep focus on the real problems and not get sucked into distracting alarmism.

Top graphic images: Waymo; Amazon; Futurism

The post A Lot Of The Reactions To Waymo AVs Using Human Intervention When Needed Feels Needlessly Alarmist appeared first on The Autopian.

Sometimes you can’t help but feel for Soviet car designers and the cars they were working on. It’s true that some completely fine vehicles made it to production during those times, including the Lada Niva and … yeah, the Lada Niva is the only one I can think of.

In any case, some absolutely wild designs have survived, showing that VAZ (Lada) and AZLK (Moskvich) designers really did try to push the envelope, but the envelope was forfeited. The VAZ-2110 (Lada 110) concept featured a Subaru SVX-style glasshouse, the ’70s AZLK-2141 concepts were closer to a Saab than the Talbot Alpine copy that emerged, and the 1986 GAZ Volga 3105 concept had windows that matched the Chevrolet Volt show car 20 years later.

A case in point is the VAZ-X and X2 concepts, dating back to the early 1980s, and visible on the wall in the GAZ-3105 shot above with some really proud-looking Soviet designers. Is that a Tupolev plane in the airbrushed poster, too?

Those were the days of the imaginative minivan, as Renault guided Matra’s groundbreaking and plastic Espace to production, Chrysler made the Voyager, Ford the Aerostar, and later GM its dustbuster Trans Sport and Lumina APV vans. Why not, then, would the Soviet automotive industry also try to create a multi-purpose vehicle of the future?

Lada displayed its first X concept in 1981. It was a swoopy, curvaceous affair with plastic panels and a cowling over a spaceframe structure. Because this was the 1980s Soviet Union, the concept car was nicotine brown, which does not really suit its shape all that well.

Headlights were mounted just beneath the curving windshield, which was cleaned with a single wiper, TGV style. The entire front end seems to consist of a removable cowling.

Surviving sketches show seating as completely configurable in different variations, ranging from a regular front-rear setup to jump seats and turning passenger seats around.

The entire vehicle was less than 14 feet long, the size of a regular hatchback, despite looking larger. Here it is with an early VAZ-2112 mockup, which is the size and shape of a Ford Escort.

The X was followed by a smaller X2 concept a year later. It shared parts of the X’s design, including headlight placement and the single wiper, but it was shorter and smaller as well as finished in blue.

Neither of these vehicles was developed to a drivable stage, and the actual Soviet Russian people carrier of the future turned out to be the 1990s GAZ Gazelle minibus that looks like a Ford Transit knock-off.

These days, AutoVAZ makes decontented front-drive compact Ladas that share parts with old Renaults and Dacias, and their styling harks back to the halcyon days of the second-generation Ford Focus sedan.

The only thing worth remembering is the Lada Niva, one of the least aerodynamic vehicles ever produced there, yet one of the most capable. For what it’s worth, the Niva is still built – as is the Gazelle.

All photos by the respective manufacturers

Top graphic image: Lada

The post Soviet Designers In The 1980s Came Up With Futuristic Cars They Would Never Be Allowed To Build appeared first on The Autopian.

The backlog of overdue major air pollution permits at the Colorado Air Pollution Control Division has grown to 128, from 111 in 2022, despite tens of millions of dollars in state investment for expanded staff and new digital processing, records show. 

State officials point to finishing a much larger number of permits each year during that time, and blame the bigger backlog on a flood of more than 100 new permit applications when Colorado was forced to permit many more sites as a consequence for ongoing violations of EPA ozone standards. They say the staff and processing expansion pushed by Gov. Jared Polis in 2022 shows 73 key Title V major polluter permits were finished in 2025, up from 13 in 2022. 

Environmental watchdogs, though, say both the growing backlog and the accelerated individual permit reviews are missed opportunities for the state to actually cut deadly air pollution. 

The division’s updates on backlogs and processing “just seems to be about them trying to figure out how better to serve polluters,” said Jeremy Nichols, who tracks the permitting system for the Center for Biological Diversity. “And where is the public in this? Where are people? Where are people’s concerns legitimately considered? There are no consequences for the delay on the renewals for the polluter. There are consequences for people who breathe air, who may be experiencing levels of air pollution that are not acceptable anymore.”

State officials should be using their power in the permitting process to require more effective technology in flaring of pollutants at oil and gas production sites, and real-time monitoring with rapid consequences for violations, Nichols said. 

In 2022, Polis and the state health department asked the legislature for more than $40 million in new general fund spending to quickly beef up the air pollution division for greenhouse gas rules and new permit engineers, experts to model expected pollution, and other experts to monitor existing pollution. 

State public health and environment director Jill Hunsaker Ryan said in an interview that years of staffing increases and training funded by the increase, alongside pending implementation of artificial intelligence-assisted permit writing, have greatly improved Colorado’s process. 

“This administration has been trying to solve issues that go back decades, including permit backlogs, outdated technology, understaffing and underfunding. And we’ve made significant progress in solving for some of these long term issues, but we haven’t yet realized all of the potential of our investments,” Ryan said. “And while these investments have allowed us to catch up quite a bit and begin to tackle the permit backlog, we’ve also experienced federal ozone downgrades.”

The EPA downgrading the northern Front Range’s health-harming ozone violations from “serious” to “severe” in 2022 “resulted in over 100 new entities required to apply for a major permit, which is a good thing for air quality, but it puts additional pressure on our backlogs, because major air permits take a long time to write and get through the process,” Ryan said. 

When the permit list blew up

The EPA’s downgrade consequences lowered the threshold of industrial uses requiring a permit to 25 tons of certain pollutants a year from 50 tons. Many of the new entities now requiring permits are oil and gas production pads, as exploration and production has increased in northeastern Colorado’s Denver-Julesburg Basin, from Weld County to suburban Aurora.

The air pollution division staff, Ryan noted, has also had to implement complex rules for each of 30 legislative bills on pollution passed from 2019 to 2025. On top of that, the Air Quality Control Commission and other state regulatory bodies have issued 80 rule revisions related to air quality standards in that time, Ryan said. 

“Integrating this level of new policies is again, good for air quality, but it takes time, and it adds a lot of complexity to the permitting process,” she said. 

The air pollution division does not have to wait for a permit rewrite to tighten limits on pollution, said division director Michael Ogletree. Each time a new rule is finalized adding caps or monitoring for polluters, those new requirements apply across a wide array of emission sources, he said. 

Representatives from Colorado’s oil and gas industry, which now produces the fourth-largest amount of petroleum among U.S. states, said they appreciate the state’s effort to “modernize and streamline” permitting. 

“Permitting timelines at the Air Pollution Control Division have grown in proportion to the additional layers of regulation that contribute to Colorado being the sixth most regulated state in the nation,” Colorado Oil and Gas Association President and CEO Lynn Granger said, in an email response to questions. “The growth in regulations and uncertainty around permitting timelines has been a drag on Colorado’s economy as well as on efforts to reduce emissions in some cases. We are encouraged to see APCD’s emphasis on improving the efficiency and accountability of the permitting process and are eager to partner with APCD on sustainable solutions.”

The Center for Biological Diversity, a national and Colorado environmental nonprofit that has successfully sued state officials over permitting delays, believes Colorado could wield more permitting power under the EPA’s Clean Air Act Title V authority to demand far more from polluters. 

“It would be more costly for industry, and it would probably be more difficult for some companies to install these kinds of monitoring systems,” Nichols acknowledged. “I know the state doesn’t want to be in the business of putting people out of business, but let’s be clear, there needs to be losers when it comes to protecting clean air. If companies can’t rise to the challenge of doing everything that is technologically feasible to control emissions and monitor emissions, I think it’s appropriate for the state to say you can’t do business in the nonattainment area. Or you can’t do business next to somebody’s house.”

Colorado’s air pollution division has employed Boston Consulting Group to oversee the expansion and reformation of the permitting system, including incorporation of Salesforce and some AI-assisted efficiencies in permit writing. The division also created a new position, chief operational improvement officer, who will be “leading the efforts to modernize permitting and improve how laboratory systems work … reducing backlogs, increasing transparency and making processes more efficient for both staff and the public,” Ryan said. 

Improvements in the process are reflected in real gains on air pollution, division officials say. New regulations and better enforcement helped cut the amount of released nitrogen oxides, a key precursor to dangerous ozone, to 156 tons in 2023 from 276 tons in 2011. Similar progress was made in volatile organic compounds, another ozone and smog precursor partially attributable to oil and gas production. 

Since the request in 2022 for a surge in state permitting assets, records and interviews show:

• Overdue Title V or “major” polluting permit applications went from 111 in November 2022 when The Sun first asked for an update to 115 in April 2023, to 128 overdue at the end of January. 
• The division received 115 extra Title V permit applications by November 2023 from the ozone reclassification to “severe” violations on the Front Range.
• Extra funding in 2022 gave the division resources to hire 30 new permitting staff. Since that year, the division has hired 28 new permit engineers and supervisors, both full-time state employees and contractors. Some of those new staff are still being trained on Colorado systems. 
• The number of completions of new or renewed Title V permits in each year has improved from 13 processed in calendar year 2022, to 39 in 2023, 38 in 2024, and 73 in 2025. 

Nichols, the clean air advocate, questioned why the state is giving itself so much credit on process rather than talking more about strengthening standards for public health. He noted that in its December presentation to the commission, division staffers called new rules and lower thresholds for permits “headwinds.” 

“The state definitely views it as just a paperwork exercise,” Nichols said. “Permitting could be used to do so much more for clean air and accountability.” 

Jay Bhattacharya, director of the National Institutes of Health under the Trump administration, appeared before the Senate Committee on Health, Education, Labor, and Pensions (HELP) Tuesday. In the wide-ranging hearing, Bhattacharya defended the chaotic and disruptive cuts at the institutes he helms while carefully wording responses related to vaccines—seemingly to avoid contradicting his boss, anti-vaccine Health Secretary Robert F. Kennedy Jr.

As Bhattacharya testified, Sen. Bernie Sanders (I-Vt.), the HELP committee's ranking member, released a report outlining the state of the NIH. The report concluded that the Trump administration is "failing American patients," and "destroying medical research through cuts to research grants, terminations of clinical trials, and the chaos it has created."

Since Trump took office, the NIH has terminated or frozen hundreds of millions of dollars for research grants, including $561 million in grants to research the four leading causes of death in America, the report found.

Destruction

Specifically, Bhattacharya oversaw the disruption of: 116 grants for cancer research, totaling $273 million; 71 grants to study heart disease, totaling $111 million; 65 grants for Alzheimer's disease, totaling $94 million; and 68 grants for diabetes, totaling $83 million. The report also identified at least 304 clinical trials that were defunded, including 69 that were for children.

In the hearing on Tuesday, senators repeatedly brought up the grant and trial cuts, emphasizing that they are disrupting, if not ending, research that could lead to biomedical advances. Senators relayed reports of scientists scaling back their lab work and some being unable to pay their graduate students. Early career scientists are looking to move abroad—while China and Europe are actively recruiting top scientific talent. Meanwhile, patients, some with dire medical conditions, have been abruptly dropped from potentially lifesaving clinical trials.

Bhattacharya was dismissive of all these concerns. "We didn't cut any funding," he claimed. "The United States remains the single best place in the world to do biomedical research."

But at other points in the hearing, he acknowledged some cuts, arguing that although grants and trials were terminated, some had been restored. "The estimates I'm hearing from my folks is that ultimately it was only a dozen or so trials that were actually terminated. Almost every single other one of them we've refocused, removed to depoliticize them and focus them on the actual science."

"Outrageous" impacts

He did not explain how studies were "depoliticized," but the Senate report noted that the NIH issued a "Staff Guidance" that all funded research be scanned for words that may not align with the Trump administration's ideology. The lengthy list (provided with the Senate report) includes words such as "diversity," "climate change," "gender," and "ethnic."

Sen. Angela Alsobrooks (D-Md.) pointed out that some of the funding was only restored as a result of a lawsuit. "So, let's be honest about that," Alsobrooks said. "Some of these... the courts had to force."

Sen. Maggie Hassan (D-N.H.) pushed Bhattacharya on the impact the cuts had on patients, asking specifically if there were any plans to study the effects on cancer patients. Bhattacharya responded, saying that there shouldn't have been any effects because he had ordered continuity of care for any disrupted trials. "If there were disruptions, then it is the responsibility of the researchers that were managing the patients, not the NIH," he said.

"That is really an unacceptable and outrageous response," Hassan responded. "You all disrupted funding. You can make an edict from Washington, DC: 'Oh, don't disrupt continuity of care.' But that can be a very complicated thing and I know that in my state, there were disruptions in these studies that have really put patients at risk."

Senators also pressed the director on the future of the NIH, noting that it has been hamstrung by the ongoing chaos, putting upcoming grant funding at risk, too. Of the NIH's 27 institutes and centers, Bhattacharya testified, "I think it's 15" that are without a director. Sen. Patty Murray (D-Wash.), meanwhile, noted that more than half of the institutes are on track to lose all their voting advisory committee members by the end of the year—and grants cannot be approved without sign-off from these committees. Bhattacharya responded that they're working on it.

Weasely answers on vaccines

In the course of the hearing, senators also tried to assess Bhattacharya's loyalty to Kennedy's dangerous anti-vaccine ideology, which includes the false and thoroughly debunked claim that vaccines cause autism.

Sanders asked Bhattacharya directly: "Do vaccines cause autism? Yes/no?"

"I do not believe that the measles vaccine causes autism," Bhattacharya responded.

"No, uh-uh," Sanders quickly interjected. "I didn't ask [about] measles. Do vaccines cause autism?"

"I have not seen a study that suggests any single vaccine causes autism," Bhattacharya responded.

But this, too, is an evasive answer. Note that he said "any single vaccine," leaving open the possibility that he believes vaccines collectively or in some combination could cause autism. The measles vaccine, for instance, is given in combination with immunizations against mumps, rubella, and sometimes varicella (chickenpox).

It would also be false to suggest vaccines in combination are linked to autism; numerous studies have found no link between autism and vaccination generally. Still, this is a false idea that Kennedy and the like-minded anti-vaccine advocates he has installed into critical federal vaccine advisory roles are now pursuing.

Later in the hearing, Bhattacharya also indicated that when he said "I have not seen a study," he was suggesting that it was because such studies have not been done—which is also false; routine childhood vaccines have been extensively studied for safety and efficacy.

"I've seen so many studies on measles vaccines and autism that established that there is no link," [to autism], he said in an exchange with Hassan on the subject. "The other vaccines are less well studied."

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Today’s diesel trucks are marvels of engineering. You can waltz down to your local Ford dealer and drive away with a truck that produces 500 horsepower, 1,200 lb-ft of torque, and can pull up to 40,000 pounds. This modern power comes with some modern responsibilities. Today’s trucks use a bevy of emissions systems to clean up their exhaust, and one of them is Diesel Exhaust Fluid. When you run out of DEF or the sensor fails, your truck may derate or go into a full limp mode. In a reversal from past regulations, the United States Environmental Agency is considering getting rid of the derating requirement entirely.

The current administration has been reversing the federal government’s stances on many issues, including how the U.S. Environmental Protection Agency (EPA) and the Department of Justice (DOJ) enforce the Clean Air Act. In the past, the federal government pursued shops that performed emissions equipment deletes on diesel trucks. Last month, we reported how the Justice Department has decided that it will no longer pursue criminal charges under the Clean Air Act for allegedly tampering with emissions devices.

EPA Administrator Lee Zeldin has spent part of his tenure making deregulation a focus of the department. One area of EPA deregulation has been easing rules for what should happen when a truck either runs out of Diesel Exhaust Fluid or the DEF equipment otherwise fails. EPA Administrator Lee Zeldin had previously ordered truck makers to stop forcing trucks into immediate limp modes due to low DEF. Now, as first pointed out by the Drive, the EPA is considering eliminating the requirement for limp mode entirely. It also wants manufacturers to report on their experiences with equipment failures. It’s a move that could make a large impact.

What Is DEF?

If you own a modern diesel car, SUV, or truck, you’re already well acquainted with DEF, and I wouldn’t be surprised if you have a jug of the stuff in your trunk or bed right now. But why do modern diesels use DEF, and why is derating these diesels when they run out a big deal?

According to Diesel Power magazine, the implementation of diesel emissions equipment was gradual. Back in the 2000s, buyers of trucks found an Exhaust Gas Recirculation (EGR) system in their engine bays. EGR systems reduce emissions by recirculating a portion of an engine’s exhaust back into the intake. Even your modern gasoline-fueled car has an EGR system. Next came the Diesel Particulate Filter (DPF), which is an exhaust aftertreatment system designed to trap particulate matter before it leaves the vehicle.

As emissions requirements demanded diesels to run even cleaner, emissions equipment evolved. The Selective Catalytic Reduction (SCR) was an important advancement in diesel emissions reduction technology. 2010 model year heavy diesels have SCR to meet the EPA’s strict regulations. Any light-duty diesel that didn’t already use SCR phased in its use during the early 2010s.

Selective Catalytic Reduction utilizes a catalyst in conjunction with Diesel Exhaust Fluid to clean the exhaust stream of a diesel vehicle. From Diesel Power magazine:

Selective catalytic reduction technology uses ammonia to break down NOx emissions produced during diesel combustion into nitrogen and water. SCR has become the technology of choice for a majority of truck and engine manufacturers to meet the stringent 2010 emissions standards set by the EPA for heavy-duty trucks. The biggest benefit of SCR for the vehicle owner is in the fuel savings the technology provides. Because SCR deals with NOx outside the engine, manufacturers are once again able to tune their engines to run more efficiently and produce more power. The increase in engine efficiency also leads to a reduction in particulate matter, resulting in less frequent regeneration of the DPF and adding to the increased fuel economy.

SCR works by first routing exhaust gases through an oxidation catalyst, which removes hydrocarbons and converts a small amount of NOx to NO2. The next step requires an injection of an aqueous urea solution, DEF, into the exhaust stream at a precise dosing rate. Exhaust fluid is converted into ammonia, which reacts with the remaining NOx in the SCR catalyst to produce harmless nitrogen and water. A final catalyst is sometimes installed downstream of the SCR catalyst, which is designed to remove any remaining ammonia from the vehicle’s exhaust.

Diesel exhaust fluid is a mixture of synthetic, high-purity, automotive-grade urea and deionized water. This liquid is clear, nontoxic, nonflammable, non-explosive, and generally nonhazardous. Additionally, DEF is classified as a minimum risk for transportation. The fluid is mixed at a ratio of 32.5 percent formaldehyde-free low biuret urea and 67.5 percent deionized water. Heavier than diesel, exhaust fluid weighs 9.1 pounds per gallon, and while it will freeze at 12 degrees, its composition and quality are not affected by freeze or thaw.

SCR is highly effective and can reduce nitrogen oxide (NOx) emissions by as much as 90 percent or so. These systems also allow manufacturers to pump out diesel engines with huge power numbers while remaining legal.

Semi-tractors often have DEF tanks capable of holding more than 20 gallons of the fluid. Depending on the model and driving situations, that fluid may last 3,000 miles to 5,000 miles or so before needing to be refilled. Mileage varies, of course.

The math changes a little for diesel pickup trucks, but the concept is the same. For example, a current-generation Ford Super Duty has a 7.5-gallon DEF tank and, depending on use case, may go roughly 3,500 miles or so between DEF refills. Older Super Duty trucks were known for going longer between DEF fills. Towing heavy, blocky trailers reduces DEF range.

It’s also common for passenger cars with diesel engines to travel several thousand miles before needing their DEF tanks refilled.

What Happens When You Run Out Of DEF

These vehicles will warn their drivers about depleting reserves, with these warnings ranging from visual reminders to audible alarms. If you fail to replenish the DEF, or the DEF system isn’t working as designed, the truck may immediately derate or enter limp mode until the issue is resolved. To use Ford as an example here, the truck may warn that it will enter limp mode in a certain number of miles, and then slow the truck down to 50 mph once the mileage threshold is crossed. If the truck believes the issue is severe, it may eventually limit the engine to idle. Other trucks have a similar system.

Many diesel owners carry spare jugs of DEF so that they can refill anywhere when needed. I always buy extra DEF whenever I test diesel trucks because I don’t know if I will run into a fuel station that doesn’t have DEF, or run into a station that does have DEF, but the price of it is absurd.

DEF systems do have an aggravating quirk, and it’s that the derates and limp modes still occur even when a part of the system fails. Unfortunately, some manufacturers and models struggle with emissions equipment reliability more than others. One infamously unreliable diesel truck is the Nissan Titan XD Cummins, which you can read my story about by clicking here. The cruel twist is that you could have a full DEF tank, but get stuck during a road trip because of a sensor or other system failure.

The EPA Rolls Back Requirements

Back in August 2025, the EPA decided to address the issue of diesel vehicles derating after either running out of DEF or a system failure. This is what the EPA announced:

Starting with model year 2027, EPA requirements state that all new diesel on-road trucks must be engineered to avoid sudden and severe power loss after running out of DEF. To fix the problem for vehicles already in use, EPA’s new guidance, developed in collaboration with manufacturers, will work to ensure that the necessary software changes can be made on the existing fleet. In addition to providing certainty to manufacturers about how EPA wants this issue resolved, the agency is not requiring separate approvals beyond that provided in EPA’s guidance. This ensures that bureaucratic steps do not delay manufacturers’ ability to put solutions into the field.

[…]

When DEF runs out or a system sensor fails, current systems can force a vehicle to drastically reduce speed or become inoperable. In many cases, vehicles are limited to as little as five miles per hour within hours of a DEF-related fault, causing significant disruptions in logistics, agriculture, and construction. Although this derate strategy was intended to ensure compliance with EPA’s Tier 4 Emissions Standards, it has caused needless frustration, operational delays, and real economic hardship for countless farmers, truckers, and equipment operators.

The EPA did not completely eliminate derates and limp modes. Instead, the new rules called for a grace period. A semi-tractor operating under the new rules would be able to drive 650 miles or 10 hours before a 15 percent reduction in torque. If the DEF issue is not resolved, a 30 percent torque reduction occurs at 4,200 miles or 80 hours past the beginning of the issue. Top speed doesn’t get limited until 8,400 miles or 160 hours, and only then will the truck slow to 25 mph. If you continue to ignore the issue with the truck in 25 mph limp mode, it’ll finally derate to 5 mph.

The timing is different for other diesel vehicles. If you have a heavy-duty diesel pickup or a diesel car, the vehicle will enter limp mode 4,200 miles or 80 hours after the detection of an issue. Limp mode top speed will be 45 mph. If that’s ignored, top speed drops to 5 mph.

Many diesel owners considered this a win. Basically, the new rules mean that if a DEF system takes a dump during a road trip, there’s enough buffer to get the vehicle back to home base to get it fixed. A grace period seems like a good idea, if only so you don’t get stuck in the middle of nowhere with a broken truck and whatever you’re towing.

Conversely, the EPA’s grace period doesn’t make a distinction between a system failure and simply running out of fluid. That implies that you might be able to intentionally drive around with an empty tank for a while.

EPA Takes It Further

Yesterday, the EPA announced further changes designed to complement the August rules. Specifically, the agency suggests that it wants to hold manufacturers accountable for DEF system failures. From the EPA:

The issue facing farmers, truck drivers, and equipment operators remains clear to the agency. Sudden speed losses and shutdowns caused by DEF system failures compromise safety and productivity. The Trump EPA’s guidance, which significantly reversed deratements, called on manufacturers to revise DEF system software in existing fleets to prevent these sudden shutdowns and give operators more time to repair faults. EPA recognizes that to improve systems, the product designs and materials for these systems must also be the highest quality possible. With today’s action, EPA is taking another step to address any potential insufficiencies with system parts to better advance future rulemaking and reduce system failures.

Under Section 208(a) of the Clean Air Act, EPA is authorized to require manufacturers to provide information needed to assess whether emission control systems are functioning properly and whether manufacturers are meeting their obligations to identify and fix defects. EPA is demanding information from the top 14 on-road and nonroad manufacturers that account for over 80 percent of all products used in DEF systems. Specifically, EPA is requiring data on warranty claims, failure rates, and repair information for Model Years (MY) 2016, 2019 and 2023 emission control products to determine whether ongoing DEF system failures are related to a specific generation of products. Manufacturers will have 30 days to provide the requested information; failure may result in additional inquiries or penalties.

What’s most interesting about the press release is a short statement that was tacked on the end, which says, emphasis mine:

EPA is actively working on its proposal for the reconsideration of the 2022 Heavy-Duty Engine and Vehicle NOx rule. It is being thoroughly assessed whether derates may no longer be necessary for compliance.

If the EPA were to decide that derates are no longer relevant, it would be a major change in how diesels are run in America. There’s no shortage of diesel owners who complain about the complexity and reliability of emissions systems. Many of these people simply delete their emissions systems, and many of those who leave their systems intact do so only begrudgingly.

If the EPA said that derates and limp modes were no longer needed to be in compliance, I suspect there would be quite a few trucks rolling around on empty DEF tanks. For some diesel owners, the only reason to fill the DEF tank is to prevent limp mode. Unfortunately, the EPA has not provided any further clarity for what that future could look like.

Regardless of what happens, I will be keeping my diesels stock. I have accepted that the emissions equipment is part of the diesel ownership experience. Besides, I like the fact that I can still enjoy diesel power, but that diesel exhaust doesn’t stink and has gone through some heavy cleaning.

We await hearing more about how the EPA plans to change diesel regulations, as we may be entering a new era for diesel emissions. We will continue to watch the EPA’s developments and write updates as they come.

Topshot graphic images: Ram/BlueDEF

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