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Britax Marathon 70-G3 Convertible Car Seat Review

August 25, 2012

Consumer Rating:

Last June 2012, Britax launched the G3 line for all its convertible car seats including the Marathon 70, Advocate 70, Pavilion 70, and Boulevard 70. The difference from last year’s models is that the G3 line are improved to have better safety features and retained the already well-appreciated other features of the convertible car seats. The new safety features are new HUGS with SafeCell Technology, Side Impact Protection, Base with SafeCell Technology, Energy Absorbing Versa-Tether, and integrated steel bars. Let us explore each great new astounding 360-degree safety features to understand the importance of it all that Britax initiated.

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Technical Specifications for Britax Marathon 70-G3 Convertible Car Seat

  • Child Weight: 5 – 40 pounds (Rear Facing); 20 – 70 pounds (Forward Facing)
  • Child Standing Height: 49 inches or less
  • Child Seated Shoulder Height:  9 – 16.75 inches (Rear Facing); 12 – 16.75 inches (Forward Facing)
  • Product Weight: 19.5 pounds
  • Product Dimensions: 18.5 x 26 x 21 inches
  • Seating Compartment Height: 23.5 inches
  • Seat Area Depth: 11 inches
  • Seat Area Width: 11  inches
  • Shoulder Width: 13 inches
  • Harness Slot Heights: 8.5 / 9.5 / 10.5 / 11.5 / 12.5 / 13.5 / 14.5 / 15.5 / 16.5 / 17.5 inches
  • Buckle Strap Depths: 5 & 7.5 inches
  • Certified for Aircraft Travel
  • Made in the USA with global components


HUGS with SafeCell Technology on Harness and EZ-Buckle System

The Britax Marathon 70-G3 Convertible Car Seat like the Boulevard 70-G3, Pavilion 70-G3 and Advocate 70-G3 is equipped with five-point harness which are tangle-free and so easy to adjust. You no longer have to rethread it or disassemble to adjust the height and it is easy to fit the child on it and he will feel so comfortable and safe. The harness straps have additional safety feature to distribute the crash forces on the strongest body parts. This is all because of the HUGS.

Harness Ultra Guard System (HUGS) Chest Pads with SafeCell Technology is located by the straps running along the harness straps. The SafeCells are designed to compress in a crash and manage energy to reduce the impact forces that your child might experience. This basically provides resistance in the event of a crash and minimize in as much possible injury by holding back your child from further moving forward. This is the main concept like a seat belt but with greater and more comfortable pull backwards. Also the HUGS are affixed on the car seat to ensure proper position on your child. This feature is just introduced this year on Convertible Car Seats G3 line.

Warning on the HUGS Chest Pads: It is strongly recommended to take out the HUGS Chest Pads for infants as they can reach them and could easily bite and cut through them. The HUGS are made of soft plastic materials that are choking hazard. To make sure you will not encounter problems such as this, ask Britax for a harder HUGS Chest Pads and customer service will send a pair for free.

The Marathon 70-G3 also has an EZ-Buckle System that has two positions. These positions actually cater to your growing child. In adjusting the buckle position, you would have to manual rethread it and lift the seat cover in making the adjustment. The buckle stays on forward facing so that the child will not sit on it and will not hurt his skin. Also, it is covered nicely with a bit of pads for more skin protection.

Here is a video on how to strap your kid on the Marathon 70-G3 or Boulevard 70-G3:

Side Impact Protection

If the HUGS protect your child from forward movements during a crash, the Side Impact Protection will protect your child from crashes on the sides. It is a system composed of the unyielding shell with deep side walls lined with energy-absorbing EPP foam. The EPP foam distributes crash forces, shields the child from vehicle intrusion or when any objects protrude because of crumpling, and helps to contain the child’s head and body from making contact with the window or door. In fact, side impact crashes are much more severe and about 30% of fatalities occur, so Britax did a good job adding it to their car seats since 1996.


Base with SafeCell Technology

We have already mentioned what SafeCell Technology is. Now we will explore why Britax also incorporated this technology on the base of the Marathon 70-G3 Convertible Car Seat like the Boulevard 70-G3, Pavilion 70-G3 and Advocate 70-G3. Since bigger kids have high center of gravity compared to infants, the SafeCell Technology will help in lowering the center of gravity and counter the forward movement so that the child will not be propelled towards the back of the vehicle’s seat. This technology has been added by Britax on their car seats since 2010.


Energy-Absorbing Versa-Tether

The Britax Marathon 70-G3 Convertible Car Seat like the Boulevard 70-G3, Pavilion 70-G3 and Advocate 70-G3 is equipped with an energy-absorbing Versa-Tether. The Versa-Tether is a strap attached to the upper two points behind the child seat. It also has a hook that attaches to an anchor in the vehicle. This tether system will allow your car seat to face forward or the rear and create a better anchor of the car seat on the vehicles seat. This will also minimize the child’s injury during a crash by diverting crash forces away from his body, minimize his movements, and helps slow down his body. The tether is further enhanced by series of loops at the top of the child seat which helps to extend the ride down or forces that are felt by the child during the crash. The energy-absorbing Versa-Tether system has been added by Britax on their car seats since 1996, while the series of loops are incorporated since 2007.


Integrated Steel Bars

The Britax Marathon 70-G3 Convertible Car Seat has integrated steel bars like the Roundabout 55, Boulevard 70-G3, Pavilion 70-G3, and Advocate 70-G3 are located on the actual frame at the lower part of the seat and above the base. The main purposes of the steel bars are to reduce the forward flexing of the child during a crash and strengthen the connection to the vehicle. This technology has been added by Britax to its series of car seats since 2010.


Premium Lower LATCH Connectors

You can also attach the Britax Marathon 70-G3 Convertible Car Seat in your vehicle through the LATCH connectors located on the lower part of the seat via a webbing strap. This is an alternate to attaching the car seat using seat belts. The LATCH or Lower Anchors and Tethers for Children are special anchors of all passenger vehicles and car seats manufactured after September 1, 2002. This is a requirement for adding safety for attaching car seats on vehicles.

Britax has designed the LATCH of the Marathon 70-G3 like the B-Safe, Chaperone, Roundabout, Boulevard, Pavilion, Advocate, and Frontier with a push button easy release to make installation and if necessary detachment from the vehicle very easy. It is like putting or removing a seat belt with an audible click. They started installing these to some of their car seats since 2001.


Built-in Lock-Offs

The Britax Marathon 70-G3 Convertible Car Seat like the B-Safe, Chaperone, Roundabout55, Boulevard 70-G3, Pavilion 70-G3, and Advocate 70-G3 is equipped with built-in lock-offs. There are actually two of them for the convertible car seats because they can be facing forward or rear. The lock-offs are inside the seat cover which are accessible during the car seat installation. These lock-offs are used when the car seat is installed using the vehicle’s seat belt instead of the LATCH system. This ensures that the lap or shoulder seat belt is snug and snaps the car seat tightly. Lock-offs have been introduced by Britax since 1996.


Anti-Slip, Contoured Base

The Britax Marathon 70-G3 Convertible Car Seat is also equipped with a contoured base that is made to prevent slipping because of the rubber edges. This keeps the car seat in fixed position for forward facing and aids in the recline for the rear facing position to make the optimum vehicle fit.


Harness Holders

The simplicity of the harness holders means more for busy parents. The main purpose of the harness holders is that it keeps the five-point harness on the sides when you place your kid in. This way it won’t get in your way, making it uncomplicated when placing your kid. And so we are very glad that Britax Marathon 70-G3 has that.


Fabric Options for Britax Marathon 70-G3 Convertible Car Seat

The Britax Marathon 70-G3 Convertible Car Seat comes with 6 fabric options. They are the Azalea, Chili Pepper, Cowmooflage, Jet Set, Onyx, and Waverly (left to right). The Jet Set is only available in Babies R Us stores.

The seat covers are removable and can be interchanged with different Marathon 70-G3 designs and can be easily cleaned. They have comfort pads for more cushion and comfort. Also it comes along with infant body pillow to make it more comfortable for the infant’s small and fragile body.


Accessories for Britax Marathon 70-G3 Convertible Car Seat

  • Infant Positioning Insert in Gray, $14.99
  • Child Cup Holder in Black, $14.99
  • Car Seat Travel Bag in Black, $69.99
  • Car Seat Travel Cart in Black, $79.99
  • Britax Marathon Cover Sets in Azalea, Chili Pepper, Cowmooflage, Onyx, and Waverly, $69.99
  • Kick Mats in Black, $15.99
  • Reversible Head/Body Support Pillow in Ivory and Gray, $29.99
  • EZ-Cling Window Shades in Black, $9.99
  • Storage Pouch in Black, $9.99
  • Vehicle Seat Protector in Gray, $29.99
  • Back Seat Mirror in Black, $19.99

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Pros and Cons


  • Easy to install
  • Easy to adjust head restraint
  • Rear or forward facing
  • Capacity is made up to 70 lbs instead of only 40
  • Feels comfortable to sit on for long drives
  • Easy adjustment for the harness straps
  • Fabric is soft and have beautiful colors
  • Rubberized edge preventing slippage
  • Good size to accommodate bigger children
  • Covered straps and buckles to protect the child’s skin
  • Easy to carry around
  • Instruction Manual is behind the lower back seat cover


  • Level indicator looks cheap
  • Maybe vehicle dependent because of its size
  • Tether instructions on the Manual is a bit confusing
  • Expensive


Consumer Ratings

The Britax Marathon 70-G3 Convertible Car Seat is being rated as 4.6 and 69% of them thinks it deserves a 5. It is currently sitting on the Best Sellers list ranking #32 in Baby category and whopping #1 in Convertible Car Seats category.


Britax Marathon 70-G3’s Price

The Britax Marathon 70-G3 Convertible Car Seat is priced at $289.99. But during this post is written, it is on sale over at Amazon at $216.98 giving you about 25% savings. Click on the Order button below to get the latest deals on the 70-G3 over at the Amazon.


Overall Impression on the Marathon 70-G3

The Britax Marathon 70-G3 Convertible Car Seat is one of the best car seats ever made. It has been designed to grow with your child until he maybe over 7 years old because of its bigger capacity and ability to be positioned in two ways appropriate for the baby’s age. It maybe bulky and expensive, but it is of good investment especially that it is equipped with the latest technology for minimizing any damage to your kid if a crash happens.

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