If you’ve driven a car built in the past decade, it’s likely you’ve dealt with auto stop-start technology before. This piece of software shuts off the car’s engine when a vehicle comes to a stop, at places like stop signs and traffic lights, to reduce idling emissions while the car isn’t moving. The second you lift your foot off the brake, the car starts back up, and you’re on your way.
Auto stop-start has gotten a bad rap, mainly due to early iterations of the system, which made stopping and starting a clunky, annoying affair. Modern versions of stop-start are far smoother to the point where, in some cars, you don’t even notice it happening.
That didn’t matter to Environmental Protection Agency (EPA) boss Lee Zeldin, who in May declared his agency would be “fixing” the rules behind stop-start tech. Now, nearly a year later, those changes have finally been ushered into law.
The “Single Largest Deregulatory Action In U.S. History”
The EPA announced today plans to finalize its goal of repealing its 2009 Greenhouse Gas Endangerment findings, which formed the scientific basis that climate change endangers human health and the environment. The move, which the EPA says will save Americans a combined $1.3 trillion in cost savings, eliminates the bedrock policies used to form greenhouse-gas emissions standards for vehicles, which, according to the EPA, have now been eliminated for vehicles built for the model year 2012 and beyond.
This move also eliminates the need for off-cycle credits, a program in which automakers were rewarded by the EPA for including efficiency-boosting tech that wasn’t measured in standard EPA testing, like solar panel roofs, energy-efficient lighting, and auto stop-start technology. The agency believes this tech wasn’t actually providing any benefit to the consumer and was driving up costs. From the announcement:
The Obama and Biden Administrations also used the Endangerment Finding to support off-cycle credits to forcibly incentivize automakers into adopting unpopular systems, undermining consumer choice. An off-cycle credit is a government-created concept that let auto manufacturers meet federal GHG standards on paper, by adding features like the almost universally hated start-stop feature, resulting in questionable emission reductions. Automakers should not be forced to adopt or rewarded for technologies that are merely a climate participation trophy with no material benefit. The Trump EPA chooses consumer choice over posturing to climate change zealots every time. Today’s announcement ends all off-cycle credits, eliminates EPA incentives for the start-stop button, and restores consumer choice. Americans will be able to buy the car they want, including newer, more affordable cars with the most up to date safety standards and that emit fewer criteria and hazardous air pollutants.
So while stop-start hasn’t been explicitly outlawed, the incentive that automakers received for including it in their vehicles is now gone.
What Does This Mean For My Next Car?
Probably not much, honestly. As more vehicles move to mild-hybrid or full-on plug-in hybrid powertrain technologies, stop-start software will continue to be a prominent feature in new cars. Even if the tech doesn’t award manufacturers government credits, it can still win them a (very) slight edge in real-world mpg over the life of the car, which buyers might care about.
Plus, as my colleague Matt pointed out when Zeldin first made this announcement, most vehicles are designed to be sold in multiple markets, with some rules stricter than others. It probably wouldn’t be worth an automaker’s time to rip out a start-stop system specifically for the American market, especially when it can still deliver actual benefits.
If anything, stop-start will continue to appear on new cars, but it might not be enabled by default after every start-up, as it is on some current cars. But don’t expect the feature to disappear for the 2027 model year.
For What It’s Worth, Start-Stop Does Make A Difference
I totally understand if you have strong feelings about stop-start systems. If they’re not well-designed, they can be absolutely infuriating to use. I’ll be the first to admit I turn off a stop-start system as soon as I get into a car that doesn’t have a good one. But in the system’s defense, there have been multiple studies and tests that have proven its efficacy.
Back in 2014, AAA tested three vehicles equipped with stop-start on the EPA’s urban driving cycle, and found it improved fuel economy by up to seven percent. AAA estimated that the system would save around $179 in fuel costs over 15,000 miles in a car that got 20 mpg. That’s not nothing.
In another test performed by Edmunds around the same time, the publication used a three-cylinder Mini Cooper, a four-cylinder BMW 328i GT, and a 5.0-liter supercharged V8-powered Jaguar F-Type R to see whether stop-start made a difference on an 80.4-mile test loop with multiple stops. All three cars saw fuel savings of 9.5% or above when start-stop was engaged.
In 2023, the Society of Automotive Engineers (SAE) published a study that concluded start-stop systems saved fuel compared to running the same routes without start-stop. In one case, fuel economy was improved by a gargantuan 26.4%. From the study:
Four vehicles were tested both with and without the feature enabled under three test cycles: the Federal Test Procedure (FTP) city fuel economy test, the US06 high acceleration aggressive driving schedule that is often identified as the “Supplemental FTP” driving schedule, and the EPA New York City Cycle (NYCC). The results were compared to measure the fuel economy and consumption effects of using the auto stop-start feature. It was found that the fuel economy improvement varied significantly between drive cycles depending on the amount and percentage of idle time during the test. The largest fuel economy improvements were 7.27% and 26.4% for the FTP and NYCC, respectively.
By now, I think most people are used to the idea of stop-start in their cars, and the tech will continue to be included in most new vehicles, evolving to be even more seamless than it is now. But for the few people who truly hate the idea of their engine turning off every time they come to a stop, it’s a win.
Top graphic image: DepositPhotos.com; EPA
I really despise the start/stop feature on gas-only cars. I feel the same way about the current administration. Going to chalk this up to a blind squirrel finding two broken clocks, or something like that.
As someone who lives in a real city, next to a stop light. This tech is actually nice. Everyone comes to a stop and now I’d say 80-90% of cars are silent. You can hear things other than the traffic for a brief moment.
For everyone outside the car the shift towards start stop, hybrid, and full EVs is great. It’s measurably improving our air quality in areas where most folks are driving newer cars.
Wait, start-stop is optional? OEMs weren’t required to add it, they *chose* to?
Preening about deregulating a ‘regulation’ (authoritative rule or requirement issued by a government agency) that isn’t actually a regulation feels a bit like, well, a self-awarded deregulation-participation trophy.
They chose to add it because they got EPA mileage credits for offering it.
I despise how the vindictive morons currently governing us politicize even simple things like regulatory changes.
I think this is a dumb change that is undoing progress on fuel efficiency and emissions, but whatever – they’re allowed to make the change while they are in charge. However, what rankles is the way they add “Biden bad, Trump good” language.
Or remember last year, when the TSA was subjecting folks waiting in airport lines for security checks to videos blaming the democrats?
Or Trump 1.0, when the Covid relief checks authorized by a bi-partisan Congress prominently featured DJT signatures claiming credit?
I don’t care how spicy the politics are. I want my bureaucracy to be boring.
“make government boring again” I can get behind that statement for sure! I would sleep better.
EPA = Environmental Pollution Agency
Trump is going to usher in the Dark Ages II: Coal Powered Boogaloo
He’s doing it for his voters who live in economically depressed areas merely because their families have lived there forever. They don’t mind dying of black lung (if they survive the mines themselves) if that work in the only field with opportunity is the cost of a relatively decent salary and they get to stay there. Sure beats moving somewhere that has opportunity and culture!
And the “manly men dig up stuff and burn it and solar and wind is girly dirty hippy stuff” mind set of so many of those supporters.
As disgusted as I am in a general sense, I’m not sure how much this coal BS is going to really matter. Nobody is going to convert back to coal. It might delay shutdowns of coal power plants, but I wouldn’t think any plans in the works are going to be stopped on the whims of a notorious pathological liar, particularly with money already spent. If the solar industry bribes him enough, he’ll be touting that next. (Are you listening, solar companies?)
In my old home town, there was a big coal plant (now CNG on a smaller, footprint with nicer architecture and a public garden).
YearsDecades ago, I looked at renting a fantastic apartment in that neighborhood with reasonable rent until the realtor mentioned that the power company gave everyone vouchers for car washes and washed the houses every 6 months (or something like that) like it was a perk, but she didn’t say anything about lung cleaning vouchers, so I passed.There is a mining war in Northern Minnesota over sulfate waste copper nickel mining in the watershed for the Boundary Waters Canoe area. The “manly men” want the few mining jobs some temp and very few permeant versus the thousands of tourism jobs and keeping a clean watershed and it comes down to gendered ideas of “real man” jobs. And the people up there are scared to death of the “culture” of Minneapolis.
I doubt that there will be any physical changes.
For now they’ll push an update that makes the auto-start-stop function stay off after you turn it off, then if the next administration is left leaning they’ll push a new update to make it always turn back on every time you restart the car.
In my experience every time you turn off an engine there’s no guarantee you can get it running again, so for the sake of moral I’d prefer my engine stay on.
Also studies during WWII showed that when we ran the factories 24/7 we had less machine breakages relative to the hours on the machines compared to pre war where they shut the factories down at night.
yeah this is the change I would make. Push a software change that allows the “turn it off” to be permanent until manual changed back to “on”. Otherwise, change nothing.
I like my start-stop function, but I would be fine with them pushing an update to leave it in the condition you last put it in. As far as extra wear and tear on the engine, yeah, there probably is some if it isn’t smart enough to wait until you reach full temperature. After the engine is warmed up, I would think it’s minimal because it’s not cooling down while I sit at a stoplight.
“Americans will be able to buy the car they want, including newer, more affordable cars with the most up to date safety standards and that emit fewer criteria and hazardous air pollutants.” Bolding was by me.
I don’t really understand the use of the word “criteria” here. I didn’t realize my cars emitted “criteria”.
Also, removing pollutants from the list of pollutants doesn’t make them less polluting.
Use of “criteria:” considering their actions, why would you expect them to consider their language?
True.
I have trained myself to just lift my foot a little off the brake peddle and the engine kicks on and does not shut off again when I am at a stop light. No need to hit a switch just a little foot twitch.
As a scientist and an educator, I am just at a loss for words. Next week will will be putting lead back in gasoline and paint.
Can’t wait. It gives it a nice sweet flavor.
In my experience, it saves nothing, but I’m not in a a seriusly urban area, so I try to turn it off, average stop has to be less than 10 seconds, usually around here just a 4-way, so it pumps more gas in to restart than it saves. If I were driving El Camino Real from San Jose to S.F. another story, but heres my truth according to data provided by my car (’21 Outback XT)
Last trip reset – 5228 miles ago
Average mileage – 23.5 mpg
Time auto-stopped -1hr 24 minutes
Fuel saved – .638 gallons
Fuel used to drive those miles – 222.47 gallons
% of fuel saved with auto stop -.003%
Estimated (conservatively) stop/start cycles -160+
Whats the environmental cost to add all this “feature” to save .003%?
The “problem” is not the autostart/stop it’s that I get the fun of having a car that only gets 23.5mpg.
But if I don’t burn it, somebody else will.
“% of fuel saved with auto stop -.003%”
I think you meant 0.3%, but point taken, it’s not helping you. On the other hand, it’s a software feature. Not having it doesn’t save anything either.
Duh need to convert %, need more coffee. Sadly cant fix my post after a reply. There is a hardware cost to it.
Multiply that small individual percentage by hundreds of thousands or millions to account for the total fleet of vehicles. A small percent of a lot is still a lot.
As someone who spent most of his life driving crappy cars that could break at any moment, I have always hated stop/start. Every. single. time. I have the fleeting thought that my car just broke down. I would love it if I could turn it off and it would stay off. That said, this EPA is evil and does not have our best interests in mind.
I would be okay with it if it would remember that you turned it off and remain off next time you drive. That it doesn’t is intentional.
My main concern is engine wear. Unless it has an electric pump to maintain oil pressure, you’re starting the engine without oil pressure, again and again and again.
Like 0w20 oil. It provides some benefit to the manufacturer on paper, but the real world consequences are negative for the consumer.
I’ve never met an otto cycle auto stop start I’ve liked. You want auto stop then atkinson cycle with a hybrid. The defeat devices are maybe $5 to $40. The automakers should have to have some way to turn the thing off or offer the defeat device free of change as I’m sure many people that dont know how to install one or that they exist. But have conditioned themselves to press the button when they start their cars.
I’m still amazed my 2022 Accord doesn’t have it (the 1.5 CVT and Hybrid do, but not the 2.0T), and somewhat amazed my 2018 Miata doesn’t (since my stick shift 2013 320i did have it). I’m glad I don’t have it, but yes, the newer ones are less intrusive than they were on that 2013.
23′ Miata doesn’t have it either.
“forcibly incentivize”
…that’s an oxymoron, right?
The EPA itself is the oxymoron
We’ve ended the war on coal. We’ve cut CO2 emissions regulations. We’ve cut diesel emissions regulations. All just in time, too. It’s been a cold winter here in NY and I look forward to the better weather to come.
I’m glad they’ve offered ZERO evidence on how gutting the EPA will save people money.
It’s simple. Automakers won’t have to spend so much to reduce emissions or hit fuel economy targets, and they’ll pass the savings on to you….probably? Yeah, for sure. It’ll trickle down. Definately.
In my experience, only one thing trickles down, and it sure does have an ammonia smell.
It’ll be a 1000, 1500, 900, even 600% savings!
Hell, I’m not greedy, I’d settle for 100% savings.
if they offered ‘evidence’ would you believe it, or just denounce the ‘evidence’?
pay-to-play science says you can prove anything you’re willing to pay for.