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Britax Marathon 70 Convertible Car Seat

5 Stars- techdad

Britax Marathon 70 front

Britax is one of the most trusted car seat manufacturer’s around. They have been making convertible car seats for the US market since 1997. Never satisfied, Britax continuously improves their products to make them safer, easier to use, and more comfortable. In August of 2010, they released their new line of convertible car seats with many improvements. Having been a Britax customer since 2007, I was excited to see the improvements they made.

My Configuration:
2000 Jetta 4DR
Forward Facing
LATCH Install


  • Supports up to 70lbs forward-facing, and 5-40lbs rear-facing
  • Supports infants with an infant positioning insert (sold separately)
  • MUCH improved/easier harness height adjustment
  • New integrated steel bars
  • Serial number located in easy to find location
  • Harness buckle can now be in two positions
  • Comfort pads now removable
  • Super easy LATCH installation
  • Certified for air travel
  • Consistently rated Very Good by Consumer Reports (though this model has not yet been tested by CR)


  • Expensive

On March 21, 2011, the American Academy of Pediatrics updated their recommendations for car seats. They now recommend that children stay in the rear-facing position until the age of 2, rather than their previous recommendation of 20lbs and 1 year of age. You can read the full press release and recommendations HERE. With these new recommendations, getting a car seat with better height and weight ratings become more important. Obviously the AAP recommendations are only recommendations and if your child exceeds the limits of the car seat, it’s better to switch them to forward-facing even if not yet 2 years old. Put plainly, keep your child in the rear-facing position for as long as possible and resist the temptation to switch them too soon.

Safety is the most important feature of a car seat that I can think of. Year in and year out, Britax seems to garner very good ratings from professional publications and consumers alike. The Marathon 70 has many safety features that have given previous Marathon’s a “Very Good” rating by Consumer Reports. As of this writing, Consumer Reports has not published any crash test results of the current Marathon 70.

The Marathon 70 has good side impact protection, though not the better “True Impact” protection that Britax’s higher end convertible car seats have. The only difference between them is described as:

Minimize side to side head movement and literally “trues” the head:
Minimizing movement and keeping the neck and spine aligned limits potential injury. A abrupt, violent change in speed may cause injury to the body. By limiting the movement of your child during a crash, you are limiting potential injury.

The Marathon 70 however, does share the new integrated steel bars with their more expensive seats that “can minimize the risk of your child being violently propelled forward and hitting the back of the vehicle seat in front of the child restraint.”

One thing that always stuck with me from the very first Britax we purchased was being told by the car seat techs at the police station and at AAA that they used Britax car seats for their own children. I’m not sure what better endorsement a car seat could get than that!

Britax Marathon 70 front kidBritax Marathon 70 side
My children have always been pretty comfortable in Britax car seats. The seat cover material in the older Britax car seats were soft and plush but they changed the material to a more nylon like material on the Marathon 70. It looks much easier to clean but it doesn’t have the nice soft feel as the older covers. The design of Britax seats tend to cradle your child and some larger children who prefer to place their arms out of the car seat or on the sides like an arm rest may find it somewhat uncomfortable. One complaint I’d read from a lot of users in the older Britax car seats was the placement of the harness buckle (crotch area). Britax must have been listening because they now provide two different positions to help find the best location for your child. Also, the harness straps have comfort pads for the shoulder area that are now removable. Some older Britax car seats had permanently attached comfort pads, which car seat techs I spoke with, recommended be removed. The pads, while providing additional comfort, can make it harder to determine the correct tightness of the harness, so unless your child is screaming bloody murder, I would probably remove them.

The Britax Marathon is smaller than the Boulevard and Advocate. We have the Boulevard and Advocate in our SUV but we elected to use the Marathon for our Volkswagen Jetta sedan. We had to remove the head rest but it fit well otherwise. It could be an optical illusion, but the new Marathon 70 seems smaller than the older Marathon. Still, if you own a small car and are considered tall or you like to recline your seat far back, you might want to buy the car seat from a retailer that has a good return/exchange policy, to make sure it will work for you. We now have a Marathon 65 CS and a Marathon 70 in our Jetta and we find the fit works well for us.

Though I haven’t installed either Marathon with a seat belt, I have with our Advocate and Boulevard; they are a pain in the butt to install. Thankfully, our Jetta has LATCH connectors which made installing the Marathon 70 amazingly simple. Just clip the two LATCH connectors into the anchors in your car until you hear them click, then put all your body weight on the car seat (using your knees) and yank the straps as tight as you can. You can also use the Versa-Tether (the strap in the top rear of the car seat) and hook it to the anchor located in your car (see your automobile’s manual). Installation took me no more than 10 minutes and adjusting the buckles and straps took another few minutes. I recommend you read through the entire manual AND watch the installation video. The video for the Marathon 70 can be viewed HERE.

The one major problem I had with the old Marathon was that adjusting the harness height required me to remove the car seat then rethread the straps. I feel like Britax read my review and custom-made the new Marathon just for us! They implemented a new system that allows you to just squeeze the handle located at the top of the car seat and glide it up or down to adjust it; no rethreading required! There is one drawback to this system though. At the highest harness height, the mechanism rises with it so it can potentially obstruct viewing out of the rear window. The best harness height system I’ve ever seen was from a competitor’s car seat that used a rotating knob located on the sides of the seat. Keep in mind that in the forward-facing position, you want the harness to be at or above your child’s shoulders. In the rear-facing position, you want the harness to be below your child’s shoulders.

The serial number sticker is easily located on the right side (facing the seat), towards the top. The serial number stickers on some of their older car seats were rather difficult to find so I’m glad Britax addressed this.

I always found washing the cover to be a hassle on our Boulevard seat and I admit that I haven’t washed the cover on our Advocate or our first Marathon. The cover on the Marathon 70 is easier to remove than my older Boulevard but it’s still recommended that you hand wash the cover with cold water and mild soap, then line dry it. Unfortunately, this means that you have to wash the cover when you know you won’t need the car seat for at least a few hours as the cover can take a while to dry. With the new material though, daily or weekly cleanups should be easier with only the biggest messes requiring the removal of the cover.

The cover comes in several different colors and designs to match your style preference.
Britax Marathon 70 AllisonBritax Marathon 70 BlueprintBritax Marathon 70 CowmooflageBritax Marathon 70 CrimsonBritax Marathon 70 OnyxBritax Marathon 70 Waverly

Britax convertible car seats have advanced safety features and are consistently rated among the best. The Marathon 70 is a good choice for smaller vehicles. Britax has also made the Marathon 70 easier to use than ever before and increased the forward-facing weight rating to 70lbs. The latest Marathon is a definite improvement over previous generations and I recommend it if you can justify the cost premium.

Available from Amazon.com.

* Review sample provided by Britax USA

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