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Cybex Eternis S SensorSafe All-In-One Convertible Car Seat Review

Snuggle Bugz | | Comments 0

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As a financially savvy parent, you may be wondering if there’s a single car seat that can be used for multiple stages of your baby’s car seat journey, so you don’t have to keep buying new ones as your baby outgrows them. 

Well, look no further! 

We’re proud to introduce the Eternis S SensorSafe All-In-One Convertible Car Seat, a family-friendly superstar that's here to make your busy life a breeze! 

If there's one thing parents adore, it's affordability without compromising on quality — and this car seat delivers exactly that. From the early days of infancy until double digits, this convertible car seat grows alongside your child every step of the way. 

In this article, we'll take you through all the fantastic features that make the Eternis S a parent's best friend on the road. So, fasten your seatbelt as we dive into the wonderful world of this highly-touted, budget-friendly, grow-with-me seat from Cybex! 

All-in-One Versatility 


  • Rear-Facing: Suitable from 4 to 50 lbs. or 17 to 48" tall   
  • Forward-Facing: Suitable from 22 to 65 lbs. or 28 to 49" tall   
  • Booster: Suitable from 40 to 120 lbs. or 44 to 57" tall 
  • Dimensions: 23.5” L x 19.8” W x 25.5” H 
  • Car Seat Weight: 26 lbs. 

A marvel of German design and engineering, the Eternis S is a versatile convertible car seat and a true investment in your child's safety.  

It offers three expandable modes to accommodate your growing child: 

In the rear-facing position, it's suitable for infants from 4 lbs. and 17” in height all the way to 50 lbs or 48” (whichever comes first). Please Note: The Eternis S MUST be installed with an anti-rebound bar in Canada.

Once your child maxes out the weight/height limit, you can transition the seat to forward-facing mode, which is suitable for kids up to 65 lbs or 49" tall. Once they're ready for a booster, the Eternis S accommodates children up to 120 lbs. and a height range of 44 to 57" tall (roughly around the age of 10!). 

While the seat has a slightly more intricate installation process than some of its rivals, once installed, it offers peace of mind for years to come. Dual-level indicators ensure the proper angle, and the innovative one-pull LATCH removal system simplifies everyday use (plus, it includes convenient LATCH storage under the seat!).  

With a 10-year lifespan, this seat truly grows with your child, making it a smart choice for the long haul. 

Snuggle up to Safety 

Safety should be your number one concern when choosing a car seat, and the Eternis S has these features in spades! 

First and foremost, it boasts Cybex’s famous SensorSafe technology in its chest clip. This smart chest clip is equipped with Bluetooth technology and connects seamlessly to the Cybex app (available for Apple or Android). With it, caregivers can receive real-time safety alerts, such as the vehicle's interior temperature, if the chest clip becomes unbuckled, and even a reminder to take a break (infants shouldn’t stay in their car seat for more than 2 hours at a time). It also alerts you if you move too far from a buckled chest clip, preventing you from accidentally leaving your child alone in the car. For more information, read our SensorSafe Car Seat Technology Review. 

Cybex also outfits the seat with a steel-reinforced frame, providing incredible strength and durability. Its energy-absorbing shell, anti-rebound bar, and base work together to reduce rebound movement and the forces felt by your child in the event of a collision. Additionally, the Linear Side Impact Protection (LSP) system, which activates when the seat is positioned next to a car door, absorbs up to 25% more impact forces during a side-impact collision! With multiple layers of protection, you’ll have supreme confidence in the Eternis S, no matter the road conditions! 

A Cozy Ride 

When it comes to comfort, this seat is second to none. Your child will always be comfortable, no matter their size or age, due to the following features:  

Headrest Innovation: The patented 3-position reclining headrest is a sheer delight! Not only does it prevent your child's head from falling forward while they sleep (ensuring a safe and comfortable sleeping position), but it also boasts a 12-position, height-adjustable design. This means it grows with your child, providing optimum protection at every stage of their development. 

Customized Recline: With its 6-position adjustable recline, the Eternis S offers correct ergonomic positioning and extra legroom! This feature not only enhances comfort but also allows your child to ride rear-facing for a longer, safer duration (which we LOVE). 

Infant-Friendly: For the tiniest passengers, Cybex includes a removable newborn inlay, offering additional support for babies between 4 and 11 lbs. 

Cozy Details: Plush harness pads and a 2-position padded buckle ensure your child travels in comfort and style. It's these little details that make the Eternis S a top choice for both parents and kids! 

Abundant Extras 

Speaking of the harness, the Cybex goes the extra mile by including a no-rethread harness with dual belt adjusters. This nifty feature allows you to achieve a snug and secure fit for your child without the hassle of rethreading straps — a real time saver for your busy life! 

The seat also incorporates magnetic buckle holders, making it a breeze for your little one to get in and out with very little effort. For added convenience, there's a removable cup holder that can be placed on either side of the seat and is even dishwasher-safe for easy cleanup! These thoughtful touches are yet another reason why the Eternis S is a standout choice for modern families. 

Eternis S for Eternity 

The Eternis S SensorSafe All-In-One Convertible Car Seat is a versatile, safe, and comfortable option for parents seeking a car seat that can adapt to their child's needs over the years. Accommodating children from infancy to around ten years old, Cybex offers parents peace of mind throughout your mini-me’s developmental stages.  

While initial installation may require some extra attention, the seat’s long-term benefits make it a worthwhile choice. Safety features like SensorSafe and robust protection mechanisms keep your child safe on the road. Add in an abundance of comfort and convenience and it’s easy to see why the Eternis S is a worthwhile investment. 

For more great all-in-one car seat options, check out Top All-In-One Convertible Car Seats of 2023.