It’s Official: Car Backseats Are About To Change Forever

On Monday, December 16th, the National Highway Traffic Safety Administration finalized a new rule that will affect all new passenger cars, trucks, and other vehicles sold in the United States.

The new requirement expands upon the existing regulation requiring cars to issue a persistent chime when drivers don’t use their seatbelts. 

Here’s what you need to know about it. 

How the Rule Will Impact New Vehicles

Mercedes-Benz

Under the change, which will take effect in September of 2027, all new US passenger cars will be required to feature rear seat belt warnings. 

In other words, if someone is sitting in the rear passenger seat and hasn’t buckled up, vehicles will be required to show a visual and audio warning at startup if a rear passenger is detected and hasn’t fastened their seatbelt. 

Specifically, the visual warning must appear for a minimum of 60 seconds. The audio warning must also involve two stages. In the first stage, an alert must sound for at least 30 seconds. A second (presumably louder) warning must also be initiated if the seat belt is still unbuckled and the vehicle moves at a speed of 6.2 miles per hour or more. 

The rule change essentially marks the conclusion of a 12-year journey that began with The Moving Ahead for Progress in the 21st Century Act of 2012, in which Congress asked the NHTSA to amend Federal Motor Vehicle Safety Standard No. 208 on occupant crash protection to require rear seat belt warnings. 

While any regulation mandating blanket changes on all cars will always be a big deal, it’s worth noting that plenty of vehicles on the road already boast this safety feature, partially because safety sells, and also because the European Union already passed a similar requirement back in 2019. 

What Impact Will the Rule Have on Safety?

BMW

Some find seatbelt warnings annoying, but there’s no denying that wearing seatbelts saves lives.

The new regulation aims to address a concerning gap in seatbelt usage that safety groups have been keenly aware of for quite some time. 

In 2022, NHTSA data showed that seat belt usage for front-seat passengers sat at 91.6% but dropped to 81.7% for rear passengers. 
The NHTSA estimates the new requirement will save 50 lives a year and prevent over 500 injuries. 

Should Drivers Worry About More False Positives?

Mercedes-Benz

Anyone who has spent significant time in a newer vehicle equipped with front passenger and seatbelt detection technology may have encountered instances where the passenger seatbelt alarm went off while driving alone. 

I’ve encountered it on more than a few occasions while driving with my dog or even with heavier loads, like a bag of groceries, sitting in the passenger seat. 

Until now, I’ve always presumed that these false positives were all related to triggering a weight or pressure sensor embedded within the passenger seat. It turns out that this is likely the source of false positives in many instances given that so-called Occupant Weight Sensors or OWS are required in modern seats and to “determine if the passenger’s side front airbag should be enabled (may inflate) or disabled (will not inflate).” 

Many drivers have also experienced other instances where light electronic items have triggered seatbelt warnings. This is because some occupant detection systems feature so-called electrostatic Capacitance Sensor Systems, which, in the most general sense, go beyond mere weight to determine if an object on a seat is a human. This information is then used to determine whether a car’s passenger-side airbag should remain off or on. 

Such sensors generally assess whether objects on a seat can store an electrical charge, like a human body. The benefit of such systems is that they can prevent random heavier objects (like a bag of groceries on a seat) from inadvertently adjusting a car’s passenger airbag status. 

One downside of this technology, though, is that even small electronic devices, like a smartphone, can turn on a passenger side airbag and, in some cases, a seatbelt warning. 

Given how much car safety technology has improved over time and that many car makers have already implemented rear seat seatbelt detection systems that aren’t driving buyers nuts, we don’t expect future cars to routinely trigger rear seat belt alarms simply because there’s stuff on the back seat. But even if it does happen from time to time, it’s still just a small price to pay for reducing car-related deaths. 

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