Ask TFL: Why Don’t Manufacturers Let You Permanently Shut Off Auto Stop/Start?

Automatic stop/start is becoming a standard across the industry

Ask TFL: Why Don't Manufacturers Let You Permanently Shut Off Auto Stop/Start?

It’s a well-intended feature, but it can also be annoying.

Stop/start systems are becoming more widespread in today’s new cars, as manufacturers aim to improve fuel economy and lower emissions. On its face, it’s a great feature to have. When you roll to a stop, these systems cut the engine out. That way, you save fuel (and stop noxious greenhouse gas emissions) when you aren’t moving. But — and there is a but — these systems also have a tendency to lurch the car back into life when you take your foot off the brake.

Even if that doesn’t bother you, there are some circumstances in which you just want the system off. But here’s the rub: Most systems don’t permanently disengage when you press the switch. When you turn the engine off then back on again, the system re-engages. Again, it’s there to improve fuel economy, but if you switch it off once, odds are you want it to stay off. This is an issue that Patrick has with his 2019 Jeep Cherokee he just purchased for his wife.

2019 Jeep Cherokee Off-Road Review
2019 Jeep Cherokee Trailhawk. [Photo: Jeep]

He wrote into us to ask why auto stop/start doesn’t stay off:

“I have just purchased [a 2019 Jeep Cherokee] and have some feedback to share with you. It’s about the feature that shuts down the engine at stops and restarts after you let off the brake. When I took the test drive, it was OK. The salesperson says you can shut it off. Well, I should have asked a bit more about that but I did not. I have found that feature to be very annoying. I do not like it. Honestly, you should be able to turn it off and leave it off. Instead, you must turn it off every time you start the car. Jeep should create an update to make that feature stay off and only come on when desired. Who missed that in research and development?

I bought the Jeep for my wife and she hates it too. I just can’t tell her I hate it. What is your feedback about it. Please sell me on it and ease my remorse.”

Why doesn’t the button turn it off permanently?

Unfortunately, manufacturers who don’t already offer the feature most likely won’t implement a permanent shut-off option anytime soon — if at all. Again, it’s back to that fuel economy thing. Car and Driver actually published an article last year covering the reason why some auto start/stop systems don’t shut off permanently.

The Environmental Protection Agency offers incentives to manufacturers who force their auto stop/start systems to switch back on. If the system is “nonlatching” — in other words, it doesn’t stay off after you switch off the car — the EPA only calculates fuel economy figures when the system is engaged. If they allow the system to be permanently defeated, then they test fuel economy with the system on and off. After that, the EPA averages the two fuel economy figures. Since that number will always be lower than it will with the system engaged, manufacturers switch it back on when you start the car again.

It’s all about those miles per gallon

Even small fuel economy improvements matter to automakers these days. That’s all down to the Corporate Average Fuel Economy standards, or CAFE. Thanks to auto stop/start systems, companies like Fiat Chrysler can boost their CAFE numbers. Doing that grants “off cycle” emissions credits that can be applied to meet their overall targets. Most importantly, it can offset the impact of less fuel efficient vehicles, like trucks and large SUVs. According to a statement Ford gave Car and Driver at the time: “EPA regulations incentivize the use of [automatic stop/start] technology because it has on-road fuel economy and greenhouse gas benefits not fully captured on EPA’s fuel economy tests. In order to quality for the incentives, [the system] must be the predominant operating mode for the vehicle, such that the driver cannot permanently disable it (emphasis added).”

There are some ways to “trick” the system, or you can buy some aftermarket devices that circumvent the “nonlatching” feature of auto stop/start systems. However, if those solutions don’t work for you, you’ll have to get used to just pressing the button every time you’re in the car. Alternatively, some cars also shut the system off if you’re in manual shifting mode, rather than just leaving it in Drive.

What do you think of these systems? Let us know in the comments!