Automakers lose emissions credits for start-stop technology under new EPA rules

S

Skye Jacobs

Posts: 2,025   +59
Staff
What just happened? The Environmental Protection Agency is stripping automakers of a key compliance tool: emissions credits for automatic start-stop systems, the software-driven technology that shuts off the engine at a standstill and restarts it when the driver lifts off the brake. The decision, announced by EPA Administrator Lee Zeldin, folds start-stop into a broader rollback of federal greenhouse gas rules that have shaped powertrain design for more than a decade.

Start-stop is a relatively small feature with a dense engineering stack behind it. Modern systems tie together the engine control unit, starter-alternator hardware, beefed-up 12-volt or dual-battery architectures, and climate-control logic to shut the engine off during idle while keeping steering assist, brake boosting, and cabin comfort online.

The control software constantly evaluates battery state of charge, coolant and cabin temperatures, steering angle, and brake pressure to decide whether it is safe and acceptable to kill the engine at a stop. If the battery is weak, the wheel is turned sharply, or HVAC loads are high, the system may keep the engine running to avoid stalling or safety issues.

Technically, the payoff is clear in the right conditions. On urban and stop-and-go drive cycles, shutting the engine at idle can yield fuel-economy gains in the mid-single to mid-20 percent range, with the largest benefits on city-style cycles where vehicles sit at lights or in congestion for long stretches.

Those savings translate directly into avoided tailpipe emissions, which is why regulators treated start-stop as an "off-cycle" technology – one that delivers real-world benefits beyond what standard lab tests capture – and awarded automakers compliance credits when they installed it across their fleets. Roughly two-thirds of new vehicles now ship with some form of start-stop logic baked into their powertrain software.

In practice, the most visible trade-off is latency. Drivers often notice a brief delay between lifting off the brake and full torque delivery as the engine restarts and the transmission reengages. That split-second pause, along with the sensation of the engine "dying" at a light, has fueled vocal complaints from some drivers and enthusiasts, even though most systems allow the feature to be switched off for a given drive.

Many vehicles, however, do not offer a permanent defeat setting, requiring drivers who dislike it to press a console button every time they start the car.

By eliminating the associated credits, the EPA is changing the incentive structure that pushed start-stop from a niche response to the 1970s oil crisis into a default feature on mainstream vehicles. Under the previous regime, off-cycle credits for start-stop and other technologies, such as more efficient air-conditioning systems, gave automakers relatively low-cost levers to pull as they chased fleet-wide emissions and fuel-economy targets.

Without that regulatory boost, automakers must decide whether to keep investing in refining start-stop hardware and algorithms, particularly for the US market, or to de-content the feature where customer pushback is strongest.

The move comes alongside two other major shifts: a formal repeal of the EPA's greenhouse gas "endangerment finding," which provided the legal foundation for regulating carbon dioxide and methane from vehicles and power plants, and a broader easing of fuel-economy and EV-promotion policies.

Together, those changes loosen the federal pressure that helped make start-stop, efficient air-conditioning, hybrids, and EVs central to product planning. For now, start-stop remains heavily deployed, but its future development in the US will hinge less on regulatory math and more on whether automakers believe the engineering gains are still worth the customer friction and added system complexity.

Permalink to story:

Automakers lose emissions credits for start-stop technology under new EPA rules

 
To add to the others comments, not only is it annoying, but the added complexity of larger/dual batteries and upsized starter motors likely negates the overall emissions reduction for most use cases.

In a laboratory environment start stop makes sense, but not really anywhere else. Glad to see regulatory bodies like the EPA making consumer friendly changes.
 
  • Like
Reactions: Underdog and bclaymiles
m4a4 said:
Nobody I know that has had the displeasure of using a vehicle with such a downgrade has been happy with it.
Nice to see that it might be going away...
Click to expand...
I liked it just fine in a rental car. No idea if I would want the maintenance burden of owning it though.
 
  • Like
Reactions: TempleOrion
As usual, not only the unwashed masses, but even those who think of themselves as well-versed in technological matters, are actually ignorant of the facts or at least in denial about them whenever it comes to something that annoys them.

Case in point in is technologies like Start/Stop, DPF, EGR and other emission reducing technologies. Whose point is not neccessarily to reduce _overall_ emissions, but to reshape the emissions in a way that's beneficial for us.

Like reducing emissions that are causining cancer. Or emissions that can be and are directly inhaled by us. Like when you're stopped and waiting in a line at a red light. And where for ex. EGR can't reduce those directly harmful emissions, because it can't be used when the engine is merely idling. Start/stop kicks in there, and saves you from a lot of emissions that your car would otherwise directly pull in from the one standing in front and next to you. And which your car would put out for the car standing behind you to pull in. And so on.

Of course all these technologies add complexity and cost, and as a consequence even emissions most of the time. But those emissions are of a very, very different nature, and don't happen in front of you, or on the road running in front of your house. Instead they happen far away at industrial facilities, where they can't be inhaled by you, and are more easily monitored, reduced, captured and neutralized anyway, just because of sheer scale alone.

So, in the end we all will get less cancer, at worst at the minimal cost of having to replace an extra EGR valve or a DPF every 6-12 years, or buy an AGM battery that costs like $30 more than a lead-acid with the same capacity. Which is obviously a great deal for virtually anyone. Who wouldn't want to NOT die 10 years earlier (or already possibly at the age of 5 or 10?) if he would only have to buy a new EGR valve for that every 6-12 years, right? That's why these things have been invented. That's how and why they work. That's why they're in use and have been made mandatory by administrations who actually cared about their _the people_, and not just about making money for the few rich people that put them into power.

In the end the decision of eliminating Start/Stop is just another anti-science, anti-health and pro-money and pro-business policy of the Trump regime, which they mostly do for the pro-money and pro-business thing (ie. for their rich buddies), but has the added benefit for them to be also apparently popular because of being percepted as an annoyance by the unwashed masses, instead as a huge benefit to their health and quality of life, that it actually is.

And which btw doesn't even survive the cost analysis, because in the end treating their respiratory diseases and cancers, which can be directly traced back to such emissions, will cost actually a lot more extra than those "pesky" EGR valves, DPFs and batteries, even when not considering all the pain, and losses in quality of life and in life expectancy.
 
Last edited:
  • Like
Reactions: human7, TempleOrion, Beerfloat and 7 others
Maybe they should just display large timers in places where traffic might be stopped for over a minute showing when the traffic will start moving again. That way it would be up to the driver to switch off their engine to both save petrol and reduce pollution. The only place I've seen this done was in Cairo Egypt but the system was a bit wasted as many drivers didn't stop at red lights anyway.

In many areas in the states it is actually illegal to leave a truck engine idling for more than 2 minutes and pedestrians can film an idling truck and actually make money from doing so. The aim is obviously to reduce pollution. There are 3400 pollution related deaths just in NY each year.
 
FF222 said:
As usual, not only the unwashed masses, but even those who think of themselves as well-versed in technological matters, are actually ignorant of the facts or at least in denial about them whenever it comes to something that annoys them.

Case in point in is technologies like Start/Stop, DPF, EGR and other emission reducing technologies. Whose point is not neccessarily to reduce _overall_ emissions, but to reshape the emissions in a way that's beneficial for us.

Like reducing emissions that are causining cancer. Or emissions that can be and are directly inhaled by us. Like when you're stopped and waiting in a line at a red light. And where for ex. EGR can't reduce those directly harmful emissions, because it can't be used when the engine is merely idling. Start/stop kicks in there, and saves you from a lot of emissions that your car would otherwise directly pull in from the one standing in front and next to you. And which your car would put out for the car standing behind you to pull in. And so on.

Of course all these technologies add complexity and cost, and as a consequence even emissions most of the time. But those emissions are of a very, very different nature, and don't happen in front of you, or on the road running in front of your house. Instead they happen far away at industrial facilities, where they can't be inhaled by you, and are more easily monitored, reduced, captured and neutralized anyway, just because of sheer scale alone.

So, in the end we all will get less cancer, at worst at the minimal cost of having to replace an extra EGR valve or a DPF every 6-12 years, or buy an AGM battery that costs like $30 more than a lead-acid with the same capacity. Which is obviously a great deal for virtually anyone. Who wouldn't want to NOT die 10 years earlier (or already possibly at the age of 5 or 10?) if he would only have to buy a new EGR valve for that every 6-12 years, right? That's why these things have been invented. That's how and why they work. That's why they're in use and have been made mandatory by administrations who actually cared about their _the people_, and not just about making money for the few rich people that put them into power.

In the end the decision of eliminating Start/Stop is just another anti-science, anti-health and pro-money and pro-business policy of the Trump regime, which they mostly do for the pro-money and pro-business thing (ie. for their rich buddies), but has the added benefit for them to be also apparently popular because of being percepted as an annoyance by the unwashed masses, instead as a huge benefit to their health and quality of life, that it actually is.

And which btw doesn't even survive the cost analysis, because in the end treating their respiratory diseases and cancers, which can be directly traced back to such emissions, will cost actually a lot more extra than those "pesky" EGR valves, DPFs and batteries, even when not considering all the pain, and losses in quality of life and in life expectancy.
Click to expand...

You talk about being "ignorant of the facts" and "anti-science", yet provide no data as to exactly how much emissions are "reshaped" using start-stop. You also conveniently leave out what is maybe the biggest downside... engine wear. When an engine is not running, oil pressure drops. The most harm/wear to an engine happens when it is started. If you start it 50 times a day vs 2 or 3 times a day, it is going to need a rebuild or replacement a lot sooner.
 
  • Like
Reactions: jeffbert, bclaymiles, ScottSoapbox and 2 others
sreams said:
You talk about being "ignorant of the facts" and "anti-science", yet provide no data as to exactly how much emissions are "reshaped" using start-stop. You also conveniently leave out what is maybe the biggest downside... engine wear. When an engine is not running, oil pressure drops. The most harm/wear to an engine happens when it is started. If you start it 50 times a day vs 2 or 3 times a day, it is going to need a rebuild or replacement a lot sooner.
Click to expand...

And you provide no data to back up your claims either.
 
  • Like
Reactions: TempleOrion, Beerfloat, techseven and 5 others
FF222 said:
As usual, not only the unwashed masses, but even those who think of themselves as well-versed in technological matters, are actually ignorant of the facts or at least in denial about them whenever it comes to something that annoys them.

Case in point in is technologies like Start/Stop, DPF, EGR and other emission reducing technologies. Whose point is not neccessarily to reduce _overall_ emissions, but to reshape the emissions in a way that's beneficial for us.

Like reducing emissions that are causining cancer. Or emissions that can be and are directly inhaled by us. Like when you're stopped and waiting in a line at a red light. And where for ex. EGR can't reduce those directly harmful emissions, because it can't be used when the engine is merely idling. Start/stop kicks in there, and saves you from a lot of emissions that your car would otherwise directly pull in from the one standing in front and next to you. And which your car would put out for the car standing behind you to pull in. And so on.

Of course all these technologies add complexity and cost, and as a consequence even emissions most of the time. But those emissions are of a very, very different nature, and don't happen in front of you, or on the road running in front of your house. Instead they happen far away at industrial facilities, where they can't be inhaled by you, and are more easily monitored, reduced, captured and neutralized anyway, just because of sheer scale alone.

So, in the end we all will get less cancer, at worst at the minimal cost of having to replace an extra EGR valve or a DPF every 6-12 years, or buy an AGM battery that costs like $30 more than a lead-acid with the same capacity. Which is obviously a great deal for virtually anyone. Who wouldn't want to NOT die 10 years earlier (or already possibly at the age of 5 or 10?) if he would only have to buy a new EGR valve for that every 6-12 years, right? That's why these things have been invented. That's how and why they work. That's why they're in use and have been made mandatory by administrations who actually cared about their _the people_, and not just about making money for the few rich people that put them into power.

In the end the decision of eliminating Start/Stop is just another anti-science, anti-health and pro-money and pro-business policy of the Trump regime, which they mostly do for the pro-money and pro-business thing (ie. for their rich buddies), but has the added benefit for them to be also apparently popular because of being percepted as an annoyance by the unwashed masses, instead as a huge benefit to their health and quality of life, that it actually is.

And which btw doesn't even survive the cost analysis, because in the end treating their respiratory diseases and cancers, which can be directly traced back to such emissions, will cost actually a lot more extra than those "pesky" EGR valves, DPFs and batteries, even when not considering all the pain, and losses in quality of life and in life expectancy.
Click to expand...
Blah Blah and Blah
 
  • Like
Reactions: bclaymiles and Strontium
sreams said:
You talk about being "ignorant of the facts" and "anti-science", yet provide no data as to exactly how much emissions are "reshaped" using start-stop.
Click to expand...
For one, this is not the flex or logical argument you think it is. If anything, it's a perfect argument _against_ the decision to abolish the Start/Stop requirement - or for any change in policy for that matter - without publishing relevant data that actually justifies it. Which the administration didn't do in this case either - neither did anyone who argued for this being a good thing. Including you (see below!).

Also, you obviuously failed to comprehend that what I did was to provided you with the correct/explanatory framework in which all the emission stuff makes sense, and in which it has to be interpreted in order to be able to assess its benefits and drawbacks. Because that's what most (if not all) commenters obviously failed to realize to begin with, and without which you can only come to an invalid/unsound conclusion whether it's a good or a bad thing, even if it would just based on personal preference.

Which doesn't really work or isn't really either, because you know, you're not only poisioning yourself (or you're poisioning not primarily yourself) with your "personal preferences" about emission controls, but are also getting actively poisoned by the personal preferences of the guy waiting in front of you in the line, and you're doing the exact same thing to the guy waiting behind you at the red light, even if his personal preference would differ.

The actual data... you're free to google it. AI Overviews says it's 4-10% reductions in fuel consumption, which also means at least that much in overall emissions. In reality it's actually a lot more like (more like >20%) just because, as already explained, harmful emission are a lot higher when the engine is just idling, and when it's efficiency drops sharply.

sreams said:
You also conveniently leave out what is maybe the biggest downside... engine wear.
Click to expand...
So, should I now make the same argument you attempted (but failed) to make, that you claim that to be the "biggest downside", but provide no actual data to back up that claim? It would be just too easy, wouldn't it be?

Instead I make the argument that everything I wrote still stands for the particular interpretation of "engine wear" that you mentioned, and which I think should have been obvious to anyone was included in my original argument.

No sane person, if offered the choice, would sacrifice his health or extra 5-10-50 years of healthy life over not having to rebuild or replace their cars or engines at, say, 150k miles instead of 200k miles.. or whatever you think the shortening effect of Start/Stop is on the life of engines in general. Which, again, is not a given in the absence of actual data, which you provide none of.

Google says: "Emission controls on cars have significantly increased life expectancy by reducing air pollution-related mortality. Studies show that reduced vehicle emissions prevented thousands of deaths annually in the U.S. (dropping deaths by ~8,000 between 2008-2017) and have potential to save hundreds of thousands of life-years globally by 2050.

  • Future Projections: Stringent controls (e.g., Euro 7) are estimated to prevent 38,000 premature deaths and 625,000 years of life lost by 2050 in Europe.
  • Global Impact: Accelerated vehicle emission standards could prevent 210,000 premature deaths globally in 2030, with 90,000 of those in China and India alone. "

    So, there's that.
 
  • Like
Reactions: TempleOrion, WestleyTDPR, TooQik and 2 others
What this, in the broader aspect at the EPA, change amounts is to permission to pollute. Good luck to all those who think "pollution is good for you." It reminds me of a phrase from a documentary about industrial pollution I saw many years ago. "Toxic waste is good for you."
 
Last edited:
  • Like
Reactions: TempleOrion, WestleyTDPR, TooQik and 2 others
FF222 said:
No sane person, if offered the choice, would sacrifice his health or extra 5-10-50 years of healthy life over not having to rebuild or replace their cars or engines
Click to expand...

You haven't established or even hinted at what impact start/stop actually has on health. You would need to show what specific impact it has on local emissions, and then you'd need to establish how that is countered by a potential increase in external emissions. You've made your entire argument without ever showing the premise to be valid.
 
Last edited:
Make sure ya politicians tell your grandkids how you cheered on the gutting of the EPA while cancer rates surged. What a time to be alive... I do lothe this invasive tech though, but anyone who recruits more than a couple brain cells to ponder this will realize that - like every othet aspect of your life - the silver lining has dark implications.
 
  • Like
Reactions: wiyosaya, TempleOrion and WestleyTDPR
wiyosaya said:
What this, in the broader aspect at the EPA, change amounts is to permission to pollute. Good luck to all those who think "pollution is good for you." It reminds me of a phrase from a documentary about industrial pollution I saw many years ago. "Toxic waste is good for you."
Click to expand...
Why put "pollution is good for you" in quotes when nobody is saying that?
 
Start-stop is one of the most absurdly retarded things you could implement on an internal combustion engine.
 
wiyosaya said:
Don't you mean Blah (cough/choke) Blah (cough/choke) Blah (cough/choke) Rudy?

Or aren't you old enough to remember the smog in the 1970's? https://en.wikipedia.org/wiki/Smog

And don't think that just because a center of smog in the 1970's was in a "blue" state, that it doesn't drift in your general direction.
Click to expand...
Sure I am old enough but smog was never a problem where I lived. I am glad CA took on smog but they over did it when they took on the reservoirs and fire hydrants
 
The funniest part is that this doesn't even ban the technology, it just removes the regulatory incentive. This acknowledges that real-world user experience matters. Engineers have known for years that start-stop annoys a huge chunk of drivers, but the regulatory pressure meant they had to include it anyway and watch people immediately disable it. If the tech genuinely saved as much fuel as claimed, automakers would keep it for the marketing advantage alone.
 
I just hope for those that have this STUPID "technology" the auto makers send out a software update to DISABLE IT!
 
You must log in or register to reply here.

Similar threads

midian182
Future robotaxis may not need brake pedals under new proposal
Replies
8
Views
38
p51d007
p51d007
S
Sony and Honda pull the plug on $90,000 Afeela EV as electric dreams stall
Replies
9
Views
196
J Oelschl
J
S
Real-world data shows plug-in hybrids use far more fuel than advertised
2
Replies
26
Views
416
Jack77
J

Latest posts

Back