Is Engine Auto Stop-Start a Problem? Not in Our Acura ADX.

Engine auto stop-start—let’s call it ESS—has become an exasperating example of how a small compromise can combust into a cultural grievance. It’s a feature designed to save a little fuel and reduce harmful emissions. Instead, fervor stoked at high levels of government has made ESS political ammunition in us-versus-them social discourse.

If automatic stop-start worked as well in every car as it does in our yearlong review 2025 Acura ADX, none of this would be a discussion.

Before writing this, I ran an experiment in the ADX: I disabled stop-start for a few weeks to see what happened to real-world fuel economy and range. The answer? Inconclusive. Even with ESS off the ADX’s cumulative fuel economy continued to tick up; my need to use it as a daily driver complicated controlling for variables like city or highway driving, weather conditions, payloads, or being late for an appointment.

But ESS was never intended to make that kind of difference. Rather, it exists under the concept that cars shouldn’t idle needlessly.

On a global scale, how much fuel any single engine burns and emissions it creates at idle is trivial. But when accounting for vehicles globally, the combined effect of ESS makes a difference. The U.S. Department of Energy has estimated that personal-vehicle idling wastes some 3 billion gallons of fuel and produces 30 million tons of CO₂ per year.

That’s a fraction of America’s total fuel appetite, but it’s still blatant waste—waste ESS is meant to reduce. A regulatory environment that penalized excess consumption and emissions spurred automakers to integrate engine stop-start systems into their cars.

Trouble is, stop-start systems can suck. In some vehicles, ESS can be rough and clunky, leading to coarse vibrations and delayed departures waiting for the engine to restart. I could understand why some drivers dislike it. Aside from the fact that using ESS isn’t mandatory, it can usually be deactivated by pressing a button or two. Worst-case scenario, it takes going through a few infotainment menus. Gotta turn it off again every key cycle? How tragic. Proper engineering minimizes powertrain wear.

Rather than just turning ESS off, many drivers have voiced their annoyance with it; their need to press other buttons for various functions is ostensibly less arduous. Now, the government institution that once supported ESS has turned against it. The Environmental Protection Agency has heard these drivers and made clear its position on the technology.

In a news release with a headline stating that ESS is “Almost Universally Hated,” the EPA says stop-start is what “many Americans refer to as the single worst feature in cars.” EPA Administrator Lee Zeldin is quoted as saying ESS is a “stupid feature,” a mere “climate participation trophy with no measurable pollution reductions.” Department of Transportation Secretary Sean Duffy calls it “idiotic” and implies that getting rid of ESS will help “make cars more affordable again.”

This release announced the elimination of off-cycle credits, the compliance credits that automakers could claim for technologies expected to reduce real-world emissions in ways not fully reflected by standard certification test cycles. ESS had a defined credit in those rules. The EPA asserts that under the shackles of off-cycle credits, “consumer choice was extremely limited to the millions of Americans who did not want [ESS] technology in their cars.” The release doesn’t mention these Americans’ freedom to not use ESS or to simply buy a vehicle not equipped with it.

What’s right and wrong in this decision has deep nuances. But if the EPA release had one inaccuracy, it was citing Duffy in saying ESS is something “every driver hates.” That’s because I don’t—our Acura ADX’s system gives little to dislike.

In the ADX, the stop-start system turns the engine off only when the vehicle has stopped completely, not while still rolling slowly, as can be disconcerting with some systems. Then, this ESS restarts the 1.5-liter turbocharged I-4 immediately and consistently, never causing a wait—the engine fires in an instant. Departures from a stop are as natural with ESS as without it.

This is duly impressive, because the ADX doesn't have a complex 48-volt mild hybrid system, which can make ESS faster and smoother, especially for larger engines. But how ESS works in the ADX leaves me totally unbothered. Actually, what became bothersome was during that test period before this article: remembering to turn it off.

My point isn’t that everyone should like ESS. It’s that ESS isn’t one thing. It’s calibration, integration, and execution. The worst systems deserve criticism. The best barely register; they might even impress. That’s just like any vehicle attribute.

If consumer choice is the goal, there are other ways to get there than declaring a feature worthless and tearing out the incentives. Regulators could focus on outcomes: require transparency, track restart quality, or make the defeat process more user-friendly. Instead, the EPA chose culture-war framing: ESS is a dire imposition, and rollback is liberation.

Stop-start may deliver only small savings per vehicle. But small savings multiplied by millions is the fundamental logic of emissions policy; it’s why automakers adopted ESS in the first place. What’s exasperating isn’t that people dislike a feature. It’s that a minor, fixable thing has become an ideological battleground, especially when potential solutions could benchmark ESS systems like the ADX’s—or just remind drivers they can hit a button.

For More On Our Long-Term 2025 Acura ADX:

• Luxury on Training Wheels?​
• Did We Get It Wrong at SUV of the Year?​
• A CVT Automatic with Paddle Shifters—Why?​