In a nutshell

A convenient seat with fantastic safety features and great quality finish. Fantastically secure, but doesn't allow you to carry your sleeping newborn

What we tested

  • Ease of installing
    A star rating of 4.5 out of 5.
  • Comfort
    A star rating of 4.5 out of 5.
  • Safety features
    A star rating of 5.0 out of 5.
  • Style
    A star rating of 4.0 out of 5.
  • Durability
    A star rating of 4.0 out of 5.
  • Worth the money
    A star rating of 4.0 out of 5.
Overall Rating
A star rating of 4.3 out of 5.


  • 360-degree swivel base, rear and forward-facing, machine-washable cover, newborn inlay included, comfortable and high-quality finish


  • Hidden instructions, limited leg room for toddlers in rear-facing position

Key features of the Cybex Sirona S i-Size:

  • Age suitability: birth to 105cm (around 4 years)
  • Rear-facing to: 4 years
  • Installation: Integrated Isofix base
  • Weight: 14.6kg
  • Features: I-Size tested, advanced side-impact protection, 360 degree rotating system, driving direction control
  • RRP: £300

Our review

Design, safety and functionality: three words that German company Cybex use when describing their range of car seats. The Sirona S i-Size launched in May 2017 and is a newer version of the popular Sirona, forming part of the Cybex Gold range along with the Sirona M2.

This exceedingly bright pink (other colours available) Cybex Sirona S i-Size car seat demands your attention, providing comfort and safety for your newborn up to age four. The award-winning brand sits at the top-end of the market - and with an RRP of £300, it’s not cheap but it is comparable in price with Nuna’s Rebl Plus i-Size Car Seat (£350) and GB’s Vaya car seat (£375). However, there are also cheaper alternatives, such as the Joie Spin 360 car seat, which costs around £249.

You can buy the Cybex Sirona S i-Size from Uber Kids, Online4Baby and other retailers.

I-Size child car seats - everything you need to know.

First impressions?

“It’s pink,” said my two-year-old son as he first spotted the car seat. There’s no escaping the bright colour of the Cybex Sirona S i-Size. It is very pink. But the design and padding of this seat feel luxurious: this is one case of comfort over style. If you’re not a fan of Passion Pink, don’t panic. It comes in other more muted colours such as Manhattan Grey, Denim Blue and Autumn Gold. Once I’d recovered from the shocking pink fabric, I was a bit alarmed to find that the car seat came with no instructions. But upon closer inspection, you’ll find them hiding behind the lining of the car seat in some sort of James Bond-esque pocket.

For future reference, look for a little book symbol (see below), which should point you in the right direction - no idea this was a thing.

A Group 0+/1 car seat, what’s the best age child for the Sirona S i-Size?

This is a two-for-one car seat, taking you from the newborn days right up to the age of four. i-Size car seats are a big trend this year, with safer rear-facing for longer seats appealing to parents. The Sirona S i-Size comes with a newborn inlay and this must be used up to 61cm - approx three months old. Your little one should remain rear-facing until at least 15 months old and the Sirona has a nifty safety feature preventing babies from being turned round too early, with the swivel being controlled by the height of the harness. Although I wasn’t able to test it on a newborn, the padding is incredibly soft and the cushioned straps are attached using poppers - making them easy to clean post baby puke. However, one thing to bear in mind is the weight. At 15kg, this isn’t a car seat you can transfer easily. And it’s not buggy travel system compatible - and you know what they say about waking a sleeping baby.

How does it install in the car?

Once you’ve found the instructions, the seat is fairly easy to fit and the warnings are clear. However, at six months pregnant and with the car seat weighing 15kg, I had to get my husband to fit it securely as my growing bump and the awkwardness of fitting the car seat and base (which come as one single unit) proved too difficult. The Sirona S uses Isofix and it is best to check CYBEX’s website to make sure your vehicle is compatible with the car seat before popping to the shops to purchase, as it cannot be used with a seatbelt alone. Two green indicators on the supporting leg show when you’ve fitted the Isofix connectors correctly and the seat is safely locked.

Does it feel secure once in place?

The car seat comes fixed to the Isofix base as one unit so once correctly fitted, it feels incredibly secure. Just remember to always make sure that the car seat is showing two green indicators on the base leg, before setting off on your journey. And never travel with the car seat facing sideways.

How is strapping your child/ren in?

There’s not a parent out there that hasn’t bumped their child’s head while trying to wrestle them into a car seat. The swivel function makes those accidental knocks a thing of the past and takes the stress out of strapping your little one in. It’s delightful: for parent and child, easing the strain on your back with the click of a button and making your infant feel like they’re auditioning for a part in The Voice. Getting the hang of the swivel is pretty simple. Sometimes it can feel a little sticky and you’ll need to push it up simultaneously as you turn the car seat but it is possible to do this one-handed, with practice. However, I prefer to use both hands as it’s easier. First, press the little grey handle under the front of the seat. Make sure the seat is in its most upright position by pushing up the handle and then rotate the car seat. Another great feature is the little hooks on the side of the seat to keep unruly belts out of the way, making it that much easier for you to get on your way.

What’s the harness like?

There’s a five-point harness that securely straps your child into place. Adjusting the harness to the correct size of your child is easy by pressing a button on the front of the car seat and loosening the shoulder belts. To make it smaller, pull on the belt at the base of the seat. The straps are padded and feel comfortable on my son’s shoulders, between his legs and around his waist - and it’s nice to see there are no red marks on his skin after unbuckling him.

What do you think of the design?

The Sirona S is big, bright and bold. It’s beautifully-curved and the material is luxuriously soft. I know bright colours are attractive to kids but the colour passion-pink is absolutely too much for me. And I can’t imagine it being all that relaxing or restful for a newborn. If like me, you’re put off by pink, the car seat does come in a range of other colours.

Does it feel sturdy?

Absolutely. The car seat feels strong and well-made. The design looks like it was built to last and it comes with a three-year warranty from the date of purchase.

What’s the headrest like?

Comfort is key if you’re keen for your baby to drift off while in their car seat. And the Sirona S headrest feels soft and well-padded and my son seemed to love it. And reassuringly, the Sirona S i-Size also comes with Energy Reduction Technology. This means that if you’re in a head-on collision, the headrest will slide down and lock into place, limiting the impact on your child’s neck. All this is great: but because it’s so padded, it can limit your toddler’s view slightly.

How many positions does the headrest have?

With 12 different height positions, this is one car seat that promises to grow with your child - up to 106cm. It’s super simple to adjust, just pop two fingers through the car seat lining and lift up. One feature I appreciated was that the headrest automatically adjusts the harness height so you know your baby is supported and in the correct position.

Does it recline?

Yes. The Sirona S i-Size offers five different recline positions when rearward-facing and three when facing-forward, making sure everyone gets a comfortable sleep in the car. Listen out for a click to know you’ve altered the car seat position securely. It’s a little bit fiddly but can be done one-handed, too, which makes it so much easier for multi-tasking mums and dads.

How comfortable is it for your child - what did your children feedback?

This car seat feels far more comfortable than others we’ve used. “Comfy,” my two-year-old says, before we drive off. And I genuinely think he is when forward-facing. However, when rearward facing he looks cramped and his little legs look uncomfortable jammed against the back of the seat. He complains quickly, there is much whining and we don’t get far before I have to stop the car and swivel him around. My son is no giant and I struggle to believe that a child would be able to face rearward comfortably up to four years old. But perhaps if you drive an SUV or an estate car, they may have more room to stretch their legs.

Tell us about its safety features?

Thankfully, I’ve not been able to test the car seat for safety myself. But I can tell you about the features, of which there are plenty. Rear-facing travel is the safest way for your tot to travel, with the risk of injury in a head-on collision reduced by more than 80 per cent - and that’s why this car seat is designed to encourage you to keep them facing rearward for longer, from birth up to 105cm. However, if like me, you have an avid traffic spotter and curious toddler and you have to turn them forward-facing from 16 months or so, the Sirona S i-Size offers Energy Reduction Technology which helps reduce the strain on your child’s neck by around 20 per cent. If you’re in a side-on collision, there’s something called an L.S.P System (a little grey handle that you flick out nearest the car door) which reduces the force of impact by around 25% and an energy-absorbing shell which absorbs the force of an impact, offering added protection for your baby. These are all features that as a parent you don’t want to think about - but to have so many gives me great peace of mind when travelling about town.

Did you try out the Driving Direction Control?

The Sirona S i-Size has a handy safety feature preventing little ones from being turned too soon, with the swivel being controlled by the height of the harness. The headrest must be higher than a red warning line on the side of the car seat. If it’s lower than and beneath the sixth headrest position, it simply won’t budge.

What do you think of the size of the car seat?

Simple to swap between cars? Don’t be ridiculous. This is a bulky car seat. Not only does it weigh 14.6kg but it comes attached to its Isofix base so it’s an awkward shape to carry. Unless you’re looking for an upper-body workout, pick a spot for your Sirona S i-Size, attach it securely and leave it be.

Will your children fit in it until they are 4 years old (up to 105 cm)?

I’m all for the added safety benefits but I find it hard to believe that a four year old could sit rearward facing without complaining for the entire journey. My two-year-old’s legs are already cramped when he’s facing rearward and we can’t go two minutes down the road without him screaming, “SWIVEL.” Saying that, once forward he looks comfortable and seems happy. This is definitely a seat I’d use up until the age of four - but only forward-facing.

Is it easy to clean?

Absolutely. There’s clear guidelines in the instruction booklet on how to remove the silky-soft fabric cover and the padded straps are attached with poppers which make them a doddle to detach and shove in the washing machine at 30 degrees. I don’t think I’ve ever tried wrestling with the covers of other car seats for fear of not being able to get them back on so this is a real win. It was simple to clean - but sadly the cover came out just as pink.

How heavy is it?

Either it’s heavy or I’m weak. Just like the older Sirona, at 14.6kg, the Sirona S i-Size is not a compact car seat you want to carry about for extended periods of time.

What design feature do you like most in the car seat?

When it comes to choosing a car seat, design is probably the last thing I think about. It’s safety first, then comfort, then design - but with the Sirona S i-Size they’re all inextricably linked. For me, the best thing is the 360 degree swivel base. This feature is fantastic. Less fuss from your toddler, less strain on your back. It’s an ingenious idea that I’ll be lost without when using other car seats.

The best rotating car seats

Is it value for money?

Cutting corners on a car seat is not something any parent should do. And although the £300 price tag is high, remember that this is one seat that will grow with your child - from newborn up to four years old. Think of it this way: we bought a Maxi-Cosi Pebble Plus (£199), then swapped to a Maxi-Cosi 2wayPearl (£225) when my son was around nine months or so - and had to purchase the ISOFIX base separately (£179). Ouch. Now that £300 doesn’t sound so bad.

What’s in the box?

  • Cybex Sirona S i-Size
  • Isofix guides
  • Newborn insert

Are there any accessories needed or available?

  • Summer cover - £45
  • Cup holder - £20

Who is this car seat best for?

Although it’s designed for use from newborn until aged four, I’d say that this car seat was best for older babies, from around ten months up - purely because I like being able to have a car seat that is travel system compatible.

What do you wish you had known before you got it?

That’s simple. I’d have liked to have known where the instructions were without having to look it up on the internet, decipher a label on the car seat and unlock a secret hidden compartment behind the car seat lining. I mean, who has time for that?

Would you recommend this car seat?

For those early newborn days where you’ll do anything to preserve sleep, no. I liked being able to take my car seat out and plonk it on my buggy, without disturbing my infant’s sleep. However, I’d recommend it from around ten months or so.

MadeForMums verdict:

The Cybex Sirona S i-Size is an eye-catching car seat that is designed with parents’ backs and the safety of children at the forefront. It’s sturdy, feels and looks well-made, lasts up to four years old - which I believe justifies its £300 price tag. However, it’s heavy and awkward to move between cars and this isn’t a car seat you should buy if you want to be able to transfer your sleepy newborn around, from car to buggy. But it’s a long-lasting, comfortable seat you will use over and over again, once securely fitted in your car.

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Product Specifications

ModelSirona S i-Size
Suitable for
Child age (approx)Birth to 4 years
Child HeightUp to 105cm
Dimensions & Weight
Car seat installationIsofix base
Travel system compatibleNo
Removeable cover for washingYes
  • i-size tested
  • 360 Swivel
  • Driving direction control safety feature
  • Energy reduction technology in forward facing
  • Adjustable headrest
  • Belt holder
Optional extrasSummer cover,cup holder