The Britax Marathon and Britax Boulevard car seats are quite similar. They are both designed for children who weigh between 5 and 65 lbs., with a height of 49 inches or less, and both offer many of the same features. However, the Boulevard costs about a bit more and has a few features that the Marathon does not.
The Marathon and the Boulevard are convertible car seats, which means you can use them for both rear-facing infants and front-facing toddlers. American Academy of Pediatrics (AAP) Guidelines say all infants should ride facing the rear until they are at least 2-years-old and have reached the maximum weight the seat allows for rear-facing.
Both the Marathon and Boulevard can be used for children weighing between 5 and 65 lbs. However, the rear-facing limit on both is 35 lbs. Depending on your child's growth, you could potentially use the seat rear-facing longer than 2 years, which the AAP says is the safest position. Once your child grows to over 35 lbs., you'll want to turn her around.
The Marathon and Boulevard both have rear and forward-facing recline, high-density foam for padding, a five-point harness system, a front button that lets you easily loosen the harness, a plush cover available in many prints and colors, and harness holders to keep straps out of the way while putting a child in the seat.
Safety features of the seats include an energy-absorbing, contoured base meant to absorb impact in a crash and ensure a snug installation in all vehicles, as well as a foam liner that absorbs and distributes crash forces, according to Britax. The Marathon and Boulevard both have the Harness Ultra Guard System, meant to cushion a child's chest and reduce forward head movement during an impact. They also have push-button lower LATCH connectors. These connect to the LATCH (Lower Anchors and Tethers for Children) system required in most vehicles made since Sept. 1, 2002. These anchors are between the car cushions and in the ceiling. They let you install a car seat without using seat belts. Both car seats also have the Versa-Tether, a strap attached at two points to the upper back part of the seat, with a hook that attaches to the tether anchor in your vehicle. This technology is designed to limit the child's head movement forward if the vehicle is in an accident. If your car is older and you must use the seat belts, both the Marathon and Boulevard have a feature to secure the belt so the car seat doesn't move more than an inch front-to-back or side-to-side, according to Britax.
The Boulevard does have a couple features the Marathon does not. While the Marathon offers side impact protection, the Boulevard has what Britax calls "True Side Impact Protection." This protection on the Boulevard comes in the form of an adjustable head restraint with walls that extend on each side of the child's head. However, both car seats have the rigid shell, deep side walls and energy-absorbing foam that Britax says offer protection in a side-impact crash. Other features on the Boulevard that are different from the Marathon include an infant body pillow, which can be helpful in positioning younger babies, and a shoulder harness you can adjust without taking the seat apart.
The other major difference is in price. The manufacturer's suggested retail price for the Marathon is $289.99, while the Boulevard retails for $319.99 at the time of publication.
The Boulevard and Marathon meet Federal Safety Standards and strict crash performance standards, according to the National Highway Traffic Safety Administration.
The NHTSA rates car seats on four "ease of use" categories using a system of one through five stars, with one star designating "poor features" and five designating "excellent features." The NHTSA gave the Boulevard and Marathon overall ratings of three or four stars for both rear-facing and forward-facing use in the various categories.
Consumers typically rate both car seats highly. On the Babies 'R' Us Website, for instance, users gave all Boulevard and Marathon models average ratings of four or five stars, out of a possible five.