Feature Friday: Auto Stop/Start Engine

Feature Friday: Auto Stop/Start Engine
The off button for the auto stop/start engine on the 2021 Kia Seltos is on the dash to the left of the steering wheel. (Photo by Jill Ciminillo)

If you haven't bought a car in the last few years, you might not be familiar with the blight called auto stop/start popping up in most cars today. So, it's worth a quick explanation because if you're in the market for a new car soon, you could be in for a rude awakening if you don't know what this is -- and how (or if!) you can disable it.

When fuel economy standards got stricter, automakers started looking for ways to cut fuel consumption in their vehicles. That's why you started to see a spate of cars that were all swoopy and aerodynamic. This is also when the blasted auto stop/start feature started to make its way into vehicles.

The basic function of this feature is to stop the engine from using fuel when it's idle -- like at a stop light or railroad crossing. In theory, it makes logical, practical sense to do something like this. In practice, (and in my opinion) it kind of sucks -- especially if you're in a vehicle where the feature cannot be disabled.

What happens is this: The vehicle comes to a complete stop, the engine shuts off. As long as your foot stays on the brake, the engine remains off. Lift your foot off the brake to prepare to move, and the engine turns back on.

Again, in theory, not a bad idea.

But in most cases, what actually happens is something like this: The vehicle sputters and shakes as the engine shuts off. The heating and cooling system is muted, so you only get fan air blown in your face. The steering wheel sometimes locks up. And occasionally, there are a couple heartbeats between when you take your foot off the brake and the engine shudders back to life. So, if you're trying to make a quick left turn into traffic, that hesitation could be just enough to cause a problem.

If this feature only activated when stopped more than say 5 seconds, it might be slightly less annoying. But living in a place like Chicago -- where there's a stop sign on every corner -- means your engine turns off then on, off then on, off then on at every stop sign. Don't even get me started on the off then on, off then on, off then on that happens when you're in stop-and-go traffic.

In case you aren't reading between the lines, I loathe this feature. I have yet to find a vehicle that implements it well enough that I don't shut it off -- that is if it can be shut off. 

Most automakers will give you a button that has an A with a circle around it (see featured image above), which allows you to turn the feature off. Yay! However, most automakers do not make this a permanent one-and-done fix. You have to turn it off every time you switch the car on, which is kind of annoying.

Even more annoying is when the automaker hides the off switch. Subaru and Volvo both hide the off switch inside the infotainment display screen a couple pages deep.

Subaru Outback Fuel Savings

The one saving grace of the auto stop/start engine feature on the 2020 Subaru Outback is that the system shows you how long the engine has been off and how much fuel you've saved. Granted, it's not much in a week, but it would build up over time. (Photo by Jill Ciminillo)

One thing Subaru does that almost makes me curious enough to leave the auto stop/start engine feature engaged: When you are stopped, it will show you how long your engine has been off and how much fuel you've saved. While the image above shows the minuscule amount I got in a week, this would build up over time and (maybe?) be satisfying enough to deal with the annoyance.

Most annoying, however, is when an automaker won't let you turn this feature off. Period. You're stuck with it. Thus far, I've only seen General Motors go this route -- but only on some of their vehicles. For example, they force auto stop/start on you in Chevrolets but Cadillacs. I've heard rumors this is changing and an off switch may be coming to Chevrolet -- at least in some vehicles -- but I haven't seen it. yet myself.

If you are stuck in a vehicle that won't let you turn it off or you mostly like it, I have found a couple of cheats to turn it off. The easiest cheat: As soon as the engine shuts down, take your foot off the brake until the engine turns back on then put your foot back on the brake. That usually keeps it off for the duration of your stop.

If you're in a manual transmission vehicle that has this feature, simply keep your foot on the clutch while at a stop and auto stop/start won't activate.

In Chevrolets that don't have an off switch, shift into manual mode and tap the plus sign on the gear shift until the display shows you're in ninth gear (or whatever the top gear is). The car will still move you through the gears normally and auto stop/start doesn't activate. I asked a GM engineer once if this would damage the car or the transmission, and they said no.

While I don't hate the idea of stop/start in theory, I just wish it would be a little smoother with the implementation -- and I really wish it wouldn't mute the HVAC system.

If I ever see a day when my husband doesn't shut this feature off (sometimes I leave it on to test his reaction -- he hates it more than I do), I'll know automakers have finally managed to work out the kinks and will circle back to this post.

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  • This seems another reason to get a hybrid car, which works sort of the opposite--the engine's off unless you need heat, in which case it comes on even if you are stopped, and it also says EV mode unavailable if it is charging the traction battery while you are stopped. On the other hand, it appears that the A/C runs off the traction battery. And I wonder what someone does with it while stopped at a traffic light when it is 103 degrees in Phoenix (like all this week).

  • In reply to jack:

    Yes. I've wondered why automakers don't do more of the mild hybrid solution rather than this herky-jerky one -- I'm sure it has to do with $$. While I haven't experienced it myself, I have heard that if it's 103 degrees out, the auto stop/start engine automatically shuts itself off so that your HVAC won't be affected. Which, again, doesn't make sense to me. If you're trying for fuel savings, why not create a system that shuts the engine off but leaves the HVAC alone?

  • In reply to Jill Ciminillo:

    The last question seems easy enough to answer: If the 12 volt battery would be running the A/C, it will soon be discharged. And, in either the on-off or hybrid situation, the engine has to run to get hot coolant into the heater. Electric heat would really drain the batteries.

  • In reply to Jill Ciminillo:

    To reinforce my last point, the 2 CTA electric buses had diesel-fuel heaters.

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