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
The post The EPA Just Eliminated Automaker Benefits For Stop-Start Tech, Here’s What That Means For Your Next Car appeared first on The Autopian.
