Consumer Reports first tested the Cosco Highback toddler-booster seat in September 2011 during a standard safety and performance evaluation of combination toddler-booster seats. These are seats that can be used with the five-point harnesses to restrain smaller children weighing 22 to 40 lbs., or with the vehicle's safety belt as a booster seat for larger children from 40 to 80 lbs. The test included the Cosco Highback and several other toddler/booster models. We purchased multiple samples of each model.
Testing was performed at an outside lab that specializes in child seat testing and whose other clients include the National Highway Traffic Safety Administration (NHTSA) and many car seat manufacturers. In a typical run, a child seat is installed on a movable sled and a child-sized dummy is installed in the seat. The sled then accelerates rearward to simulate the actual forces the child and seat might encounter in a frontal-impact collision.
Below are the details of what happened in each round of our testing. For an overview of our Cosco Highback results, including a response from the manufacturer, please click here.
Our initial crash tests simulated a head-on 30-mph crash and used a 35-pound test dummy which represents a 3-year-old child, in accordance with standards for speed and impact crash simulations found in the Federal Motor Vehicle Safety Standard for child restraints (FMVSS 213). As always, we had our own certified child passenger seat technicians on site during the testing and used the manufacturers' instructions for seat installation.
We tested two Cosco Highback samples, both with labels indicating a production date of March 12, 2010. One seat was installed using the Lower Anchors and Tethers for Children (LATCH) and the other using a three-point (lap-and-shoulder) seat belt. Both installations used the top tethers. Though federal testing procedures don't require testing with three-point systems, we take that extra step because most current vehicles are equipped with lap-and-shoulder belts rather than lap-only seat belts.
Results: In both of these seats, the plastic shell cracked severely near the center front harness adjuster – which is the mechanism between the child's legs that is used to adjust and hold the harness that restrains the child in the seat. This allowed the harness to loosen.
The seats that had cracked had been purchased in May 2011 at the same time as we purchased samples of the other models for our comparative tests. As is our normal procedure when we discover a problem in a test, we then bought additional samples of the Cosco Highback and tested two of them at the outside lab. One bore a manufacture date of May 23, 2011 and the other June 24, 2011. Neither cracked during the test. On closer inspection, we noticed that these 2011-produced models appeared to have thicker plastic and other modifications in the same areas where the 2010 samples had cracked.
None of the other toddler/booster seats tested showed cracking in the harness adjuster area.
To further investigate whether the different production dates affected the performance of the seats in the adjuster area, we conducted additional crash tests using the 35-pound dummy with four more Cosco Highbacks – two that were manufactured in March 2010, and two that bore dates in May 2011.
Results: The two March 2010 seats both developed minor cracks and areas of whitening that is an indicator of stress in the plastic around the adjuster, but cracks were not large or severe enough to allow the harnesses to loosen. The two samples manufactured in May 2011 did not show signs of stress or cracking. As in Round One testing, for both the earlier and later production years, one seat from each date period was installed using the LATCH system and the other with the 3-point lap-and-shoulder belt.
Based on the varying degrees of stress and cracking exhibited in samples from the March 2010 production, and in order to see how the seats would perform with the maximum allowable weight in the harness, we then tested four additional Cosco Highbacks with the test dummy weighted to 40 lbs. These included two seats with March 2010 production dates purchased from an online retailer in October 2011, and two seats produced on Oct. 26, 2011 that were purchased in December from a major retail store in Connecticut.
For our Round Three tests, lead weights were attached to the thigh and torso areas of standard 35-pound dummies to achieve the 40-pound maximum the manufacturer specifies for harnessed use of the seat.
Use of a weighted dummy is not a procedure used in our normal test protocol, but because some of the samples of the seat had cracked in crash tests using 35-pound dummies, we were interested to know what would happen if the seat held a child at the top end of the permitted weight range. For comparison, we also used the 40-lb. dummies and LATCH installation to test three other toddler-booster models designed to handle children up to 40 lbs. in harness mode.
Once again, one Cosco Highback seat from each production period was installed using the LATCH system and the other using the 3-point lap-and-shoulder belt. For tests utilizing the weighted dummies, we looked only at the structural integrity of the seat.
Results: We saw no cracking in the following models tested with the 40-lb. dummies: Evenflo Chase, Safety 1st Summit or Safety 1st Vantage. (Both of the Safety 1st seats are also made by Dorel Juvenile Group, manufacturer of the Cosco Highback.) The Cosco Highback manufactured in March 2010 that was installed with the LATCH system had cracking around the center front adjuster with loosening of the harness that was similar to Round One results. In the other Cosco Highback – the one attached with lap-and-shoulder belt – there was only moderate cracking and no harness loosening. And there was no cracking near the center front adjuster in either of the two Cosco Highback samples manufactured in 2011.
For an overview of our Cosco Highback results, including a response from the manufacturer, please click here.