In a nutshell

Award-winning i-Size car seat suitable for use rear facing from newborn to age 4, and forward facing from around 16 months

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 5.0 out of 5.
  • Durability
    A star rating of 5.0 out of 5.
  • Worth the money
    A star rating of 4.5 out of 5.
Overall Rating
A star rating of 4.8 out of 5.


  • Looks great, really solid, rear facing until 4, parts move easily, detaches from base


  • Heavy to lift with base

Cybex has followed on from its stylish Sirona with an updated model, whose key feature, like the original, allows your little one to sit rearward-facing until 4 years old - a position tests show offers more protection than forward-facing seats.


The Sirona M2 was released to bring the popular 2012 model inline with new Europe-wide i-Size regulations.

Brought out in 2016, it's got lots of new, neat, intuitive features, which make it easy to use, and which offer reassurance to parents that it is correctly installed.

The Sirona M2 is already winning accolades, and was awarded gold in the rear facing for longer car seat category of the MadeForMums Awards 2017.

Compared to other car seats, the Jané Gravity i-Size car seat (£349) is also suitable from birth until 4 years old and meets the new i-Size regulations. It doesn't detach from the base however, whereas the M2 does. The Gravity, though, does rotate 360 degrees, which is a great feature for getting access to your child.

The Joie iAnchor Advance i-Size car seat (£169) is another contender in this class, but its ISOFIX base is sold separately (£114.95), while the Recaro Zero.1 i-Size seat (£399), is more expensive but it does rotate and includes the base.

Meanwhile, for those wanting rear-facing even longer, the Diono Radian 5 (£295) is rear facing from birth up to 6 years old.

Buy the Cybex Sirona M2 i-Size car seat from Amazon.

Is the Sirona M2 i-Size compatible?

Yes, it is! The Sirona M2 is tested to the latest safety standard, ECER129, but the original Sirona has always been tested to exceed the required safety standard set by the ECER44 legislation that runs concurrent to 129.

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What is different from the old Cybex Sirona car seat?


Both the Cybex Sirona and Sirona M2 i-Size are rearward facing up to 4 years, but there are key differences.

The Sirona M2 can be detached from its base, which Cybex calls the Base M, with a click of a few buttons. The same base fits Cybex's Aton M, an infant carrier.

The Sirona has its base incorporated into the seat, so doesn't provide the option to use an infant carrier. The Sirona seat also swivels on its base to give easy access to the child and make removing them easier, but the M2 does not rotate.

The other main difference is that when your little one is forward facing in the Sirona M2, a harness is used. With the Sirona, it has an impact shield.

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Is there anything you would have wanted to know before buying the car seat?

Only that it doesn't rotate like the original Sirona. This is a big attraction for many, I imagine.

How does it install in the car?

As an i-Size car seat, the Sirona M2 comes with ISOFIX. So is locked into place using your car's ISOFIX fittings (if you've not used ISOFIX before, the car seat has two extendable arms which clip onto bars at the base of the backrest of your car seat. Most modern cars should have ISOFIX fittings).


Everything you need to know about ISOFIX

Before you click the ISOFIX connector into place, you have to unfold and lock into place the supporting leg, connected to the bottom.

Next click the ISOFIX fittings into place, listening for the click.

The supporting leg should then be extended down to the footwell, and locked into place, ensuring extra safety and stability.

The excellent thing about this is the built-in indicators on the ISOFIX and support leg. These show you green if your car seat is correctly fitted, and red if it's not fitted properly, which is the ultimate reassurance. I always get paranoid about whether a car seat is correctly installed, as they're so fiddly to install, but so important; any extra reassurance is welcome.

Is it easy/hard to install?

The Sirona M2 was really easy to install. The instructions were clear - it took minutes to put in.

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Does it feel sturdy?

Yes, very! It's something I noticed straight away. It's one of the sturdiest-feeling car seats I've used, yet it's so sleek!

How comfortable does it feel?

It's really cosy. It kind of reminds me of an armadillo shell, because of its curved shape and strength; but it's nicely cushioned on the inside.

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How is strapping your child in?

The Sirona M2 has a five-point harness - one with straps over the shoulders and from between the legs. These can be difficult to piece together when you first use them, but once you get your head round them they're easy to clip together. They're never a joy with a child struggling to escape though!

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What's the headrest like?

Great. Really well designed. Some not-so-well-designed headrests allow your child's head to constantly slip to the side when they nod off, jolting them back awake - which any adult trying to sleep on an EasyJet flight can appreciate is very annoying! Not so the Sirona M2. It's got a decent headrest.

How many positions does the headrest have?

12! There shouldn't be any point when your little one isn't in the right position. It adjusts really smoothly too.

How many seat positions are there? Is it to adjust the seat?

It boasts a one hand recline system, which works really smoothly and has 3 reclining positions when the seat is facing forward, and 5 when it's rearward facing.

How portable and easy is it to get in and out of the car?

It clicks in and out of its base really easily, with the press of a few buttons, and it's really light to lift. It's not a struggle at all to get out of the car.

Is it travel system compatible?

The base - called Base M - also fits Cybex's infant carrier the Aton M. Cybex says that as the Sirona M2 is designed to also accommodate the older child, it wouldn't be practical to lift such a weight in and out of the car. Unless you're Arnold Schwarzenegger (that's me saying that. Not Cybex).

What do you think of the design?

It's really classy and elegant. All smooth edges and sleek. I think it's the best looking car seat I've come across. It looks expensive.


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

It's obvious that thought has gone in to making it fairly slim. Cybex says it's been designed to fit into small cars as well as larger vehicles.

The seat can be used rear-facing or forward-facing - what age child can sit in each position?

The Sirona's big selling point is that it can be used rear-facing until your child is 105cm tall (around 4 years old).

Cybex advises to keep your child rear-facing for as long as possible as the evidence is this reduces the risk of injury in a head-on collision by more than 80% compared to forward-facing seats with a harness.

However, in this seat you can turn your little one around to face forwards once they've reached the minimum height of 76cm and 16 months old.


Do you think your child will fit into the seat for the full 4 years?

Cybex says the seat can accommodate children up to 4, whichever way it's facing. Facing forward, I think any child aged up to 4 could comfortably sit in it. It has multiple headrest positions, and plenty of space to grow with your child.

Facing rearwards, I think a long-legged child may have to scrunch up a little bit.

How does the integrated side impact system work?


Cybex call this the Linear Side Impact Protection, LSP. You just pop out the side nearest the car door. Cybex says you must only use the side protection on the door side. If the car seat is installed in the middle of the rear seat, then the side impact must not be used.

Is it easy to clean?

Yes. A quick sponge clean got rid of a few yucky stains for us.

Has it or the parent company won any awards?

Cybex is one of the most awarded in Europe. It has over 250 safety awards and lots of Red Dot design awards. Although it's a new seat, the Sirona M2 has already been awarded test winner in the test 11/2016 of ADAC and Stiftung Warentest, Germany's leading consumer testing organisation. And, of course, it was awarded gold in the MadeForMums Awards 2017.

What's in the box?

  • Cybex Sirona M2 i-Size car seat
  • ISOFIX base

Additional extras

  • Summer seat cover £45
  • Cupholder £20
  • ISOFIX guides £10

Is the product value for money?

£350 is a lot of money. Especially one that only seats children up to 4 years old.

On the other hand, it's excellently designed - both in regards to its looks and safety. The price is also comparable to other sitting rearwards for longer car seats.

So, if you have that kind of money; what price do you put on child safety? It's definitely a worthwhile investment.

Do you have to buy lots of additional extras?

There are some extras you can buy, like a summer seat cover and a cup holder, but these are nowhere near essential. Everything you need is included in the box.

What did you think of how the various parts adjusted?

It's a really well-designed car seat. All the parts move very smoothly.

Would you use it from newborn?

Yes! The size seems fine for a newborn and the safety the seat offers is very reassuring for such a little one.

MadeForMums verdict:

The Sirona M2 is an excellent car seat, perhaps one of the best I've used. It's packed full of up-to-date safety features, and looks so sleek. Its asking price is not to be sniffed at, but it offers good value for money - a lovely car seat. Anyone who wants to invest in a car seat which excels in safety features, and is up to date with modern regulations.

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Product Specifications

ModelSirona M2 i-Size car seat
Suitable for
Child age (approx)Birth to 4 years
Child HeightUp to 105cm
Dimensions & Weight
Car seat installationIsofix base
Travel system compatibleNo
Positions of carry handleNone
Removeable cover for washingYes
  • Forward and rear-facing
  • Can be rear-facing to age 4
  • I-size compatible
Optional extrasSummer seat cover (£45); Cupholder (£20); ISOFIX guides (£10)