Britax Marathon Convertible Car Seat – Improved G3 & G4

Britax Marathon G4 Convertible Car SeatThe Britax Marathon Convertible Car Seat is packed with Britax innovative car seat safety features, comfortable and secure with thick shock absorbing foam and proprietary LATCH system. It is easy to install, with removable car seat cover that makes it simple to clean.

Moderately priced amongst Britax next generation convertible car seats, consumer rave reviews have shown that the improved Marathon G3 and G4  are popular choices for parents with newborns.

The Britax Marathon has remained well like by parents for its great value for money since it entered the market with the Marathon 70,  but you can now get more benefits out of it for your baby with the G3, even better bang for your money with the G4.

Read the rest of Britax Marathon 70 convertible car seat review below:

Price Review

Britax Marathon G4.1 Convertible Car Seat

Britax Marathon G4.1

Table of Contents (Jump ahead!)

  1. Child’s Safety Protection
  2. Child Age and Size
  3. Ease of Use
  4. Child’s Comfort
  5. Easy to Clean
  6. Size and Fit
  7. Other Features
  8. Consumer Reviews
  9. Pros & Cons
  10. Feature Summary in Video!

Child’s Safety Protection

Research by Children’s Hospital of Philadelphia et al found that “…head injury is the leading cause of death for children up to 12 years old involved in vehicle crashes and comprises 65% of injuries in both frontal and side impact crashes …”

The safety of your child is the first consideration in choosing any car seat, and Britax Marthon 70 convertible car seat has been designed with revolutionary safety features to provide maximum protection for your child in the event of a vehicle accident.

Britax Marthon 70 is built with Safecell technology that enables car seats to compress in a crash, greatly reducing a child’s centre of gravity, and this counters the forward motion of the car seat which would have propelled a child towards the front seat, causing injury to the child.

With integrated steel bars, Britax Marathon 70 convertible car seat’s connection to the vehicle is strengthened and this further reduces the forward motion of your child in the event of a car crash.

Incorporated in Britax child car seat design since 1996, the Side Impact Protection feature of the Britax Marathon car seat is generously layered with shock absorbing EPP foam that keeps the spine and neck aligned, and deep side walls that distribute crash impact and protects your child’s body from touching parts of the vehicle that may cause injury in a car crash.

Britax Marathon 70 Tether System

The tether on Britax Marathon 70 features a staged-release energy absorbing design that again slows forward motion, greatly reducing crash impact that may reach the child. It also features a two point attachment that reduces forward movement while firmly holding the top of the convertible car seat.


Britax Marathon 70 has a five-point harness that is tangle free, holds the child securely and distributes crash forces evenly across the strongest parts of the child’s body thereby minimizing crash injuries.
The safety features designed into Britax Marathon 70 just keeping going, with a click and safe snug harness which has a reassuring audible device to indicate when your child is safely and comfortably harnessed.

Front and side impacts are the most frequent sources of injuries in a car crash, and the extensive safety features in Britax Marathon 70 of convertible car seat work together to provide a child with the best protection a car seat can offer in a car crash.

(Back to Top)

Child Age and Size

Just as the BRITAX Marathon 70 convertible car seat is packed with important safety features for your child, one other feature that makes it very popular is, you guessed it!– Yes, it is convertible and will serve a child as he or she grows from baby to toddler.

This High-capacity convertible car seat will allow your child to use the same safe, comfortable, and secure five-point harness car seat from baby, through the toddler years, without the need to invest in a new car seat.

The BRITAX Marathon 70 can be used as a rear facing car seat for babies from 5 to 40 pounds, and as they grow into toddler, it is easily converted to forward facing car seat from 1 year and 20 pounds, up to 70 pounds.

(Back to Top)

Ease of Use

The safety features of a car seat may be highly rated, but if it is so difficult to use that it leaves you frustrated every time you strap in your child, there is a good chance that the car seat will not offer your child the protection intended due to improper use.

Britax Marathon 70 convertible car seat uses Premium lower LATCH connectors with push-button that allow you to easily install the seat in a vehicle using the LATCH system. The LATCH connectors are attached to the lower part of the child seat via a strap that is also known as webbing. The installation gives a reassuring audible click when the connector is securely attached into place.

Britax Marathon 70 Latch System                                                               Britax Marathon 70 Anchor

When you want to remove the car seat from the vehicle, simply push the red button on the anchor and the connector is effortlessly released.


All vehicles manufactured since September 1, 2002 in USA are required to have LATCH anchors for attaching Child car seats, but with BRITAX exemplary commitment to innovations in Child car safety, the LATCH connectors has been featured in BRITAX child car seats since 2001.

(Back to Top)

Child’s Comfort

The Rear and Forward Facing Reclining feature of BRITAX Marathon 70 allows you to adjust the car seat to a position most comfortable for your child, allowing for additional leg room for your growing child. Combined with generously layered shock absorbing EPP foam, the convertible car seat is padded with High Density Comfort Foam that gently cushions your child, and an infant body pillow to provide extra comfort.


Without disassembling the harness straps, the Quick-Adjust, No-Rethread Harness is easily adjusted to ensure it comfortably but firmly fits your child’s shoulder height.

(Back to Top)

Easy to Clean

The cover is easily removed for cleaning. BRITAX Marathon 70 features a plush, Easy-Remove Cover for easy cleaning without disassembling or uninstalling the child seat. Spot cleaning, or hand wash is advised as machine wash may degrade the fire retardant fabric. Wash the seat cover in cold, mild soapy water, rinse, squeeze out excess water and hang to dry.

(Back to Top)

Size and Fit

Britax Marathon 70 measures 21 x 18.5 x 26 inches, and weighs 18 pounds out of the box. It is recommended for a minimum child’s weight of 5 pounds, and a maximum weight of 70 pounds.

(Back to Top)


Other Features

Beside the great safety, ease of use and comfort features of the Britax Marathon 70 convertible car seat, you will also find these other equally amazing features in the car seat:

    • Harness Ultra Guard System (HUGS™) – provides resistance to forward movement during a crash
    • Two Buckle Positions for allowance as your child grows
    • Built-in Lock-Offs that ensure a snug lap and shoulder belt installation with minimal effort
    • Anti-Slip, Contoured Base that grips and protects the vehicle seat while offering optimum vehicle fit
    • Convenient Harness Holders that keep harness straps out of the way when placing your child in the car seat
    • Britax Marathon 70 is Certified for Aircraft Travel

(Back to Top)

Consumer Reviews

As at the time of writing this review, the Britax Marathon 70 has been rated on Amazon by 72 customers who have purchased and used the car seat. The reviews indicate that customers are very pleased with the convertible car seat, and some customers are so pleased they made additional purchases:

“We love this car seat so much we bought one for both our kids for each car. It was very easy to install and is very secure. Even though we have leather seats the seat still does not move…(read more)”

“We love this seat, it was very easy to install. And it’s very safe – after correct installation, this thing does not move at all! … I have two of these and wouldn’t purchase anything else …(read more)”

You can be sure to get a great deal on Amazon, especially if you buy during one of the regular product discounted sales.  The Marathon 70 comes with free shipping which is nice, plus a no hassle return policy that is also reassuring.

(Back to Top)

Pros & Cons


Tick Good The extensive safety features of Britax Marathon 70 are huge, and customers absolutely love the reassuring features.

Tick GoodEasy installation of the car seat with the LATCH system is a hit with customers.

Tick GoodWill your child ever make a mess, you bet! but cleaning the car seat is a lot easy with Marathon 70 easily removable cover.


Cross out Some customers find Britax Marathon 70 expensive and were hesitant before making a purchase, but once they put the car seat into use, their comments generally are that it is money well spent.

Cross outOne customer in particular likes the car seat but says it looks ugly! But hey, beauty is in the eye of the beholder! Customer added though she loves the car seat features regardless.

(Back to Top)

Britax Marathon Car Seat Video Review

(Back to Top)

Price Check

Compare Britax Marathon G3 and G3 Infant Car Seats

The G3 and G4 are later models of the Britax Maratthon range of Convertible Car Seat.

Though earlier models like the Marathon 70 are still available and can be cheaper to purchase, the G3 or the G3 would be a better choice so you and your baby can benefit from all the benefits of improved features.

Britax Marathon G4 Convertible Car Seat OnyxBritax Marathon G4 Convertible Car Seat OnyxBritax Marathon G4.1 Convertible Car SeatBritax Marathon G4.1 Convertible Car Seatprice

If you have any question about this review, please leave a comment below and I will reply. You may also have other thoughts to share, your comments are welcome.

Speak Your Mind