The auto stop-start feature, which automatically turns off a car’s engine when stopped and restarts it when the brake is released, has become a common fuel-saving technology in modern vehicles. Initially introduced in Japan with the 1974 Toyota Crown and later popularized in hybrid vehicles, the system can reduce fuel consumption by 7 to 26 percent depending on driving conditions, according to a 2023 report by the Society of Automotive Engineers. Tests by automotive resource Edmunds have shown it typically delivers around 10 percent savings in city traffic.

Despite its fuel efficiency benefits, the system has faced criticism from some drivers and officials. Transportation Secretary Sean P. Duffy referred to it as an “idiotic” requirement that drivers universally dislike, while Environmental Protection Agency Administrator Lee Zeldin described it as a “stupid feature” that damages vehicle components and produces little environmental benefit. Under the Trump administration, the EPA removed incentives that previously encouraged automakers to include auto stop-start systems, suggesting this would lead to a reduction in their adoption.

The technology became more widespread following fuel economy and emissions regulations introduced during the Obama administration. Automakers earned carbon reduction credits by equipping more vehicles with auto stop-start to meet stricter standards. However, industry representatives note the system was never federally mandated and that current regulatory changes affect only incentives rather than forbidding the technology’s use. Hyundai, for example, confirmed ongoing compliance with emissions regulations and continues to evaluate vehicle technologies based on customer feedback and efficiency goals.

Consumer reports reflect a mixed but improving reception. Early adopters experienced issues such as abrupt engine restarts, but complaints have diminished as manufacturers refined the technology for smoother operation and improved control placement. More than 75 percent of new vehicles produced in 2026 are expected to include auto stop-start as a standard feature, according to JD Power.

Concerns about increased wear on batteries and starting components have been addressed by industry data. Kelley Blue Book notes that modern vehicles are designed to handle the additional engine cycles, and a 2015 study by the U.S. Department of Energy’s Argonne National Laboratory found no significant increase in starter system replacements due to the feature.

While some drivers find the engine pauses distracting, others appreciate the fuel savings amid rising gasoline prices that have recently exceeded $5 per gallon in parts of the United States. The system also allows continued use of accessories like air conditioning and radios during stops, unlike manually shutting off the engine. Drivers retain the option to deactivate auto stop-start in most vehicles if preferred.

As automakers plan production several years in advance, the removal of regulatory incentives is unlikely to lead to an immediate decrease in the presence of auto stop-start systems on new cars. The technology remains a prominent element in efforts to enhance fuel efficiency and reduce emissions in internal combustion engine vehicles.