President Trump’s Environmental Protection Agency (EPA) recently announced that it would end the “off-cycle” credit that manufacturers receive for installing engines that automatically turn off when vehicles come to a complete stop and restart when drivers take their feet off the brake pedal or accelerate. The purpose of the stop-start feature is to improve fuel efficiency and reduce carbon emissions in internal combustion engines. In 2012, the Obama EPA instituted a credit for manufacturers to install the feature in vehicles, which led to an increase in the number of vehicles with stop-start. The feature, however, was not liked by vehicle owners. In 2022, more than 1% of all automobile defect complaints collected in a Transportation Department database were related to this feature.
According to the 2024 EPA Automotive Trends Report, in 2012, less than 1% of vehicles had the start-stop feature. In 2016, about 9% of passenger cars included the feature. Now, about two-thirds of cars are manufactured with the start-stop feature. According to Consumer Reports, most cars allow drivers to temporarily turn off the start-stop feature, but they must do so each time they drive. The start-stop systems can cause a slight pause as they restart the engine, so drivers may want to turn the feature off when quick acceleration is needed to enter traffic.
One analysis found that fuel economy improvements varied significantly across 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% across two of three drive cycle tests performed, using four different vehicles. Note that the savings occur under city driving conditions, not highway driving, and the highest were under New York City conditions. The greatest benefits are for city-style cycles, where vehicles sit at lights or in congestion for long stretches. According to an AAA test that used a mix of highway and city testing to get a broader average, the fuel economy savings ranged from 5% to 7%.
The Trump administration, however, has linked such features to higher automobile prices and has used the rescission of the Obama-era endangerment finding to eliminate the credit. According to EPA Administrator Lee Zeldin, the regulatory overhaul will help save consumers an average of $2,400 when they purchase a new car. He also noted that not only do many people find the start-stop feature annoying, but it kills the vehicle’s battery without any significant benefit to the environment. Additionally, the feature allowed automakers to claim greenhouse gas credits without delivering real-world emission reductions or benefits to human health.
Engine Starters Have a Limited Life Span
An engine starter only has so many starts in it before it burns out. So, cars that use stop-start typically feature specialized starters designed for longevity. According to CarBuzz, the starters may use different carbon and copper compositions in order to sustain more frequent use, they may turn over more slowly than conventional starters in order to reduce wear and tear, or they may use a combination of advanced technology to keep the starter from wearing down as quickly as a conventional starter motor.
Despite technology’s ability to improve a starter’s longevity, a starter still needs replacement after turning over so many times, as its life depends on how frequently it is used, not on miles or years. For the Subaru Crosstrek or the WRX, for example, one of the top 10 most common repairs listed on RepairPal is for a no-start diagnosis, usually costing around $88 to $111. According to RepairPal, a new starter costs $125 to $158 for labor and $330 to $472 for parts, totaling $455 to $629.
Analysis
The Trump administration is stopping the “off-cycle” credit that manufacturers receive for the stop-start feature on autos, a feature that U.S. drivers strongly dislike. The feature’s future development in the United States will depend on whether automakers believe the engineering gains are worth the customer resistance, cost, and added system complexity, not on federal credits.
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